FT: Celtic 5-1 St Mirren - Daizen Maeda steers in early on; Reo Hatate slots home from spot with Ben Taylor dismissed for the handball; Oh Hyeon-gyu nets first Celtic strike
Mark O'Hara scores from the spot for visitors Greg Kiltie is brought down only for Matt O'Riley & Hatate to counter
AET: Ayr 4-1 Elgin - Kane Hester puts underdogs ahead before Fraser Bryden levels at the death; Ben Dempsey & Dipo Akinyemi (2) score in ET
FT: Dundee Utd 0-1 Kilmarnock - Kyle Vassell nods in from Danny Armstrong corner; Loick Ayina sent off late on for hosts on debut
FT: Livingston 0-3 Inverness CT - Billy McKay gives Championship club advantage before Sean Welsh makes it two; McKay nets third
FT: Raith Rovers 3-1 Motherwell - Jamie Gullan & Sam Stanton score; Kevin van Veen lashes in scrappy effort before Ismael Goncalves scores on debut
Celtic v St Mirren (17:30)
Just a wee reminder, this evening's tie is one of just two games using VAR in Scotland this weekend.
Only ties played at top-flight grounds which are chosen for live TV coverage must use the technology, otherwise it's at the discretion of the clubs involved.
So we can look forward to a night free of controversy... right?
Image source, SNS
Dipo Akinyemi
Dipo Akinyemi nets his second of the match to extend Ayr's lead.
Image source, BBC SportCeltic v St Mirren (17:30)
Celtic boss Ange Postecoglou says speculation linking him with the Leeds job is only a compliment if he "takes any notice of it".
"All I'm focussed on is doing a job well here and making sure I uphold the responsibility I have," he tells BBC Sportsound.
"We've had a really strong training week and that should get us ready for a good challenge today."
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Celtic v St Mirren (17:30)
Stephen Robinson makes two changes to his St Mirren side after last weekend's home defeat to Hibernian.
Out go Charles Dunne and Greg Kiltie for Declan Gallagher and Richard Taylor as Robinson aims to make his team more solid
Image source, SNSDeclan Gallagher comes into the St Mirren defence
Dipo Akinyemi
Dipo Akinyemi slots in Ayr's third from close range and they look very much on course for the quarter-finals.
Image source, BBC SportCeltic v St Mirren (17:30)
For Ange Postecoglou, it's just the one switch to the line-up that started last Sunday's 4-1 win at St Johnstone.
It comes in midfield as Reo Hatate makes way for David Turnbull, who makes his first start since Celtic's 5-0 win over Morton in the previous round last month.
Image source, SNSDavid Turnbull returns to the Celtic starting line-up
Celtic v St Mirren (17:30)
Kheredine Idessane
BBC Sport Scotland at Celtic Park
With a place in the quarter-finals up for grabs, Celtic's recent results suggest St Mirren will have plenty of work to do to keep the home side at bay.
They've won their last seven matches in a row, scoring 22 goals in the process and letting in just the solitary one. The last team to beat them? Real Madrid at the beginning of November.
Since then, Ange Postecoglou's side have played 15, won 14 and drawn one.
Celtic v St Mirren (17:30)
Celtic: Hart, Johnston, Carter-Vickers, Starfelt, Taylor, McGregor, Turnbull, Mooy, Jota, Maeda, Kyogo.
Substitutes: Bain, Haksabanovic, Abada, Kobayashi, Oh, Iwata, O'Riley, Hatate, Forrest.
St Mirren: Carson, Fraser, Gallagher, Taylor, Strain, Baccus, O'Hara, Gogic, Tanser, Greive, Main.
Substitutes: Urminsky, Shaughnessy, Kenny, Small, Flynn, Kiltie, Offord, Jamieson, Watt.
Celtic v St Mirren (17:30)
Scottish Cup. Saturday night. Name a better duo.
Image source, SNSScottish League 1
Airdrieonians 3-4 Dunfermline
Scottish League 2
Albion Rovers 0-1 East Fife
Dumbarton 2-1 Annan
Forfar 1-1 Stenhousemuir
Stranraer 0-0 Bonnyrigg Rose
Ben Dempsey, penalty
Ben Dempsey puts Ayr in front for the first time with a penalty in extra time.
Ross Draper fouled Dipo Akinyemi and Dempsey struck well from 12 yards.
Image source, BBC SportRaith Rovers are into the quarter-finals of the Scottish Cup for the first time since 2015 after overcoming Motherwell.
Jamie Gullan, from the spot, and Sam Stanton in the first half had Raith cruising.
A response was delivered through Kevin van Veen but debutant Esmael Goncalves wrapped the tie up late on with a powerful strike from an acute angle.
Image source, SNSKyle Vassell's second-half header takes Kilmarnock past Premiership rivals Dundee United into the Scottish Cup quarter-finals.
An unhappy afternoon for United with debutant Loick Ayina sent off late on.
Image source, SNSKyle Vassell (number 23) got the all important goal in the 55th minute
Morton take the three points against Queen's Park in the Scottish Championship.
The Spiders took the lead through Grant Savoury but two quick George Oakley goals and Jack Baird's effort had Morton 3-1 up before Connor Shields' consolation.
Image source, SNSJack Baird's goal proved to be the winner
Inverness Caledonian Thistle's unexpected Scottish Cup run continues as they upset European contenders Livingston to book a place in the quarter-finals.
Beaten in the fourth round by Queen's Park, Billy Dodds' side were given a reprieve to the last 16 after the Spiders fielded an ineligible player.
And they made the most of their second chance with a Billy Mckay double and a Sean Welsh header proving more than enough to upset their top-flight opposition.
It's the sixth time Caley Thistle have made it to the quarter-finals in the past decade.
Image source, SNSBilly Mckay (far left) scored the first and third Inverness goals
Livingston 0-3 Inverenss CT
Jane Lewis
BBC Sport Scotland at the Tony Macaroni Arena
Some Livi fans have seen enough. They've watched their side try to get back into this cup tie but it's been frustrating viewing as the home side have missed chances or faced solid defending or goalkeeping.
As for Inverness fans, I don't think they're leaving this ground anytime soon. They're willing their side on to add to their already impressive score.
Image source, SNSSean Welsh (right) scored the second Inverness goal
Extra time to be played
Ayr United looked to be on their way out of the Scottish Cup after Kane Hester's first-half opener but Fraser Bryden has forced extra time.
Image source, SNSKane Hester struck in the 41st minute
Fraser Bryden
Fraser Bryden's shot draws Ayr United level in the 90th minute.
Image source, BBC SportEsmael Goncalves
A terrific goal from the debutant from an acute angle with sheer power beating Liam Kelly.
Image source, BBC Sport