Partick Thistle manager Ian McCall tells BBC Scotland: "The pitch is the same for both teams, that's pretty obvious. I think the groundsman has done a great job to make it as good as it is. It's not ideal for either team, but you've just got to get on with it.
"It's an opportunity for both teams to get to the next round of the Scottish Cup. I think that's more relevant in terms of where Dundee United are right now than us, but nobody will get an easy game at Firhill and we very much want to get to the last eight.
"Alex Jakubiak has come off the bench to great effect in the last two games and I'm really excited to watch him play."
SNSCopyright: SNS
A close up of the Firhill pitchImage caption: A close up of the Firhill pitch
'It ain't going to be pretty'
Partick Thistle v Dundee United (15:00)
Derek Ferguson
Former Rangers and Hamilton midfielder on Sportsound
Quote Message: I didn't realise the pitch was in such bad nick. In the wide areas, it's dreadful. It ain't going to be pretty. It might well be an old-fashioned cup tie
I didn't realise the pitch was in such bad nick. In the wide areas, it's dreadful. It ain't going to be pretty. It might well be an old-fashioned cup tie
SNSCopyright: SNS
Partick Thistle have been sharing Firhill with Queen's Park this seasonImage caption: Partick Thistle have been sharing Firhill with Queen's Park this season
Hearts drop Boyce, Anderson starts for Livi
Heart of Midlothian v Livingston (15:00)
Northern Ireland striker Liam Boyce drops to the Hearts bench along with defender Taylor Moore and midfielder Peter Haring.
In come Northern Ireland right-back Michael Smith, midfielder Cammy Devlin and on-loan Brighton & Hove Albion left-back Alex Cochrane following the midweek 2-1 home defeat by Dundee.
Livingston show just one change from the midweek league draw with Ross County, with striker Bruce Anderson replacing Odin Bailey.
O'Hara back for Motherwell, Dons drop Ramsay
Motherwell v Aberdeen (15:00)
Fir Park captain and Scotland full-back Stephen O'Donnell remains on the Motherwell bench after the midweek 2-0 defeat away to Dundee United.
Nathan McGinley, Callum Slattery, Jordan Roberts, and Kaiyne Woolery drop out of the starting XI to join O'Donnell among the replacements.
In come strikers Kevin van Veen and Connor Shields, plus left-back Jake Carroll, while midfielder Mark O'Hara returns from injury for his first start since early November.
Aberdeen have got two back-up goalies today, with newly arrived veteran Craig Samson alongside teenager Jamie Shingler. Gary Woods continues to deputise for the ill Joe Lewis.
Adam Montgomery and midfielder Funso Ojo are reinstated after the 3-2 loss to the wing-back's parent side, Celtic, with Dylan McGeouch and Calvin Ramsay making way.
SNSCopyright: SNS
Teenager Calvin Ramsay is given a break by Aberdeen after the defeat to CelticImage caption: Teenager Calvin Ramsay is given a break by Aberdeen after the defeat to Celtic
Top-scorer Austin back for Kelty
St Mirren v Kelty Hearts (15:00)
It’s a case of if it isn’t broke, don’t fix it for St Mirren boss Jim Goodwin as he opts for the same starting XI that beat St Johnstone in midweek.
SNSCopyright: SNS
League 2's top scorer Nathan Austin is in from the startImage caption: League 2's top scorer Nathan Austin is in from the start
Kelty boss Kevin Thomson makes three changes to his starting line-up from the team that beat Elgin City 4-0 last weekend.
Striker Alfredo Agyeman and defender Scott Hooper are out, along with on-loan defender Daniel Finlayson ineligible against his parent club today.
Ross Philp and Jordon Forster come into the starting XI in Paisley today, with League 2 top scorer, Nathan Austin, also back in Kelty's starting XI.
Jakubiak's first Thistle start
Partick Thistle v Dundee United (15:00)
Thistle make two changes from the midweek 3-3 draw with Inverness Caledonian Thistle.
Defender Tunji Akinola is unavailable and midfielder Cammy Smith drops to the bench.
In comes left-back Stephen Hendrie, while forward Alex Jakubiak makes his first start on loan from Dundee.
United name an unchanged side from the one that beat Motherwell 2-0 in midweek.
They do welcome Charlie Mulgrew back into the squad and the former Scotland defender takes his place on the bench.
Aberdeen sign veteran goalkeeper Samson
Motherwell v Aberdeen (15:00)
Aberdeen have signed goalkeeper Craig Samson, with the 37-year-old named on the bench for the Dons.
Samson retired as a player in 2018 but was signed by Hibs as a coach and registered as a player for the 2020-21 season - although he didn't play.
He will, predominantly, be a goalkeeping coach at Pittodrie due to a knee injury suffered by Gordon Marshall.
However, with first choice Joe Lewis unavailable and youth goalkeeper Tom Ritchie suffering a "serious injury" yesterday afternoon, Samson will also be back-up for Stephen Glass' side.
SNSCopyright: SNS
Craig Samson has signed a short-term deal as a player-coach with AberdeenImage caption: Craig Samson has signed a short-term deal as a player-coach with Aberdeen
Here's what we have lined up for you in the Scottish Cup this afternoon.
There's two all-Premiership ties and three lower league sides hoping to upset the big boys.
BBCCopyright: BBC
Listen to Sportsound
BBC Radio Scotland
Sportsound coverage of today's games is just about to begin on BBC Radio Scotland.
Among the pundits joining host Richard Gordon are former Scotland internationals Kenny Miller, Willie Miller, Leanne Crichton, Derek Ferguson and Cammy Bell.
Click the wee window at the top of this page to listen.
SNSCopyright: SNS
Up for the cup
Welcome to last-16 weekend in the Scottish Cup, with five fixtures kicking us off over a staggered afternoon and evening, culminating in Rangers' visit to Annan Athletic, with one Aaron Ramsey due to make his first Light Blues start.
There's also some big games in the Championship and League 1.
So stay with us for the build-up, live commentary and post-match reaction on the website and BBC Radio Scotland's Sportsound.
Live Reporting
Clive Lindsay
All times stated are UK
'Nobody will get it easy at Firhill'
Partick Thistle v Dundee United (15:00)
Partick Thistle manager Ian McCall tells BBC Scotland: "The pitch is the same for both teams, that's pretty obvious. I think the groundsman has done a great job to make it as good as it is. It's not ideal for either team, but you've just got to get on with it.
"It's an opportunity for both teams to get to the next round of the Scottish Cup. I think that's more relevant in terms of where Dundee United are right now than us, but nobody will get an easy game at Firhill and we very much want to get to the last eight.
"Alex Jakubiak has come off the bench to great effect in the last two games and I'm really excited to watch him play."
'It ain't going to be pretty'
Partick Thistle v Dundee United (15:00)
Derek Ferguson
Former Rangers and Hamilton midfielder on Sportsound
Hearts drop Boyce, Anderson starts for Livi
Heart of Midlothian v Livingston (15:00)
Northern Ireland striker Liam Boyce drops to the Hearts bench along with defender Taylor Moore and midfielder Peter Haring.
In come Northern Ireland right-back Michael Smith, midfielder Cammy Devlin and on-loan Brighton & Hove Albion left-back Alex Cochrane following the midweek 2-1 home defeat by Dundee.
Livingston show just one change from the midweek league draw with Ross County, with striker Bruce Anderson replacing Odin Bailey.
O'Hara back for Motherwell, Dons drop Ramsay
Motherwell v Aberdeen (15:00)
Fir Park captain and Scotland full-back Stephen O'Donnell remains on the Motherwell bench after the midweek 2-0 defeat away to Dundee United.
Nathan McGinley, Callum Slattery, Jordan Roberts, and Kaiyne Woolery drop out of the starting XI to join O'Donnell among the replacements.
In come strikers Kevin van Veen and Connor Shields, plus left-back Jake Carroll, while midfielder Mark O'Hara returns from injury for his first start since early November.
Aberdeen have got two back-up goalies today, with newly arrived veteran Craig Samson alongside teenager Jamie Shingler. Gary Woods continues to deputise for the ill Joe Lewis.
Adam Montgomery and midfielder Funso Ojo are reinstated after the 3-2 loss to the wing-back's parent side, Celtic, with Dylan McGeouch and Calvin Ramsay making way.
Top-scorer Austin back for Kelty
St Mirren v Kelty Hearts (15:00)
It’s a case of if it isn’t broke, don’t fix it for St Mirren boss Jim Goodwin as he opts for the same starting XI that beat St Johnstone in midweek.
Kelty boss Kevin Thomson makes three changes to his starting line-up from the team that beat Elgin City 4-0 last weekend.
Striker Alfredo Agyeman and defender Scott Hooper are out, along with on-loan defender Daniel Finlayson ineligible against his parent club today.
Ross Philp and Jordon Forster come into the starting XI in Paisley today, with League 2 top scorer, Nathan Austin, also back in Kelty's starting XI.
Jakubiak's first Thistle start
Partick Thistle v Dundee United (15:00)
Thistle make two changes from the midweek 3-3 draw with Inverness Caledonian Thistle.
Defender Tunji Akinola is unavailable and midfielder Cammy Smith drops to the bench.
In comes left-back Stephen Hendrie, while forward Alex Jakubiak makes his first start on loan from Dundee.
United name an unchanged side from the one that beat Motherwell 2-0 in midweek.
They do welcome Charlie Mulgrew back into the squad and the former Scotland defender takes his place on the bench.
Aberdeen sign veteran goalkeeper Samson
Motherwell v Aberdeen (15:00)
Aberdeen have signed goalkeeper Craig Samson, with the 37-year-old named on the bench for the Dons.
Samson retired as a player in 2018 but was signed by Hibs as a coach and registered as a player for the 2020-21 season - although he didn't play.
He will, predominantly, be a goalkeeping coach at Pittodrie due to a knee injury suffered by Gordon Marshall.
However, with first choice Joe Lewis unavailable and youth goalkeeper Tom Ritchie suffering a "serious injury" yesterday afternoon, Samson will also be back-up for Stephen Glass' side.
LINE-UPS from Fir Park
Motherwell v Aberdeen (15:00)
Motherwell: Kelly, Ojala, Mugabi, Solholm, Carroll, Donnelly, Goss, O'Hara, Efford, Shields, Van Veen.
Substitutes: Fox, O'Donnell, Lamie, Woolery, Shaw, Slattery, Cornelius, Tierney, Grimshaw, Amaluzor, Roberts.
Aberdeen: Woods, McCrorie, Bates, Gallagher, Montgomery, Ojo, Brown, Ferguson, Besuijen, Hayes, Ramirez.
Substitutes: Samson, Shingler, MacKenzie, Emmanuel-Thomas, Jenks, McGeouch, Ramsay, Barron, Kennedy.
LINE-UPS from Tynecastle Stadium
Heart of Midlothian v Livingston (15:00)
Heart of Midlothian: Gordon, Smith, Kingsley, Souttar, Baningime, Devlin, Halliday, Cochrane, McKay, Simms, Sibbick.
Substitutes: Stewart, Haring, McEneff, Woodburn, Boyce, Mackay-Steven, Atkinson, Moore. Ginnelly, Pollock.
Livingston: Stryjek, Devlin, Fitzwater, Obileye, Penrice, Holt, Omeonga, Pittman, Forrest, Nouble, Anderson.
Substitutes: Maley, Boyes, Longridge, McMillan, Kelly, Montano, Lewis, Sibbald, Shinnie, Bailey, Chukwuemeka.
LINE-UPS from The SMISA Stadium
St Mirren v Kelty Hearts (15:00)
St Mirren: Alnwick, Fraser, Shaughnessy, Dunne, Tait, Power, Gogic, Ronan, Kiltie, Jones, Greive.
Substitutes: Lyness, Urminsky, McCarthy, Millar, Tanser, Flynn, Erhahon, Henderson, Erwin.
Kelty Hearts: Jamieson, Black, Forster, Cardle, Austin, Barjonas, Higginbotham, Tidser, Philp, Ngwenya, O'Ware.
Substitutes: Donaldson, Reilly, McNab, Biabi, Agyeman, Cameron.
LINE-UPS from Firhill Stadium
Partick Thistle v Dundee United (15:00)
Partick Thistle: Sneddon, McKenna, Hendrie, Holt, Mayo, Crawford, Tiffoney, Bannigan, Graham, Docherty, Jakuniak.
Substitutes: Firth, Turner, Smith, Bell, Murray, MacIver, Stanway.
Dundee United: Siegrist, Smith, McDonald, Niskanen, McNulty, Edwards, Butcher, Levitt, Harkes, Graham, Watt.
Substitutes: Eriksson, Clark, Akinola, McMann, Meekison, Neilson, Mochrie, Macleod, Moore, Cudjoe-Anim, Mulgrew.
Post update
Let's get going with the team line-ups...
Three chances of cup shocks
Scottish Cup fifth round
Here's what we have lined up for you in the Scottish Cup this afternoon.
There's two all-Premiership ties and three lower league sides hoping to upset the big boys.
Listen to Sportsound
BBC Radio Scotland
Sportsound coverage of today's games is just about to begin on BBC Radio Scotland.
Among the pundits joining host Richard Gordon are former Scotland internationals Kenny Miller, Willie Miller, Leanne Crichton, Derek Ferguson and Cammy Bell.
Click the wee window at the top of this page to listen.
Up for the cup
Welcome to last-16 weekend in the Scottish Cup, with five fixtures kicking us off over a staggered afternoon and evening, culminating in Rangers' visit to Annan Athletic, with one Aaron Ramsey due to make his first Light Blues start.
There's also some big games in the Championship and League 1.
So stay with us for the build-up, live commentary and post-match reaction on the website and BBC Radio Scotland's Sportsound.