The first decent passing move of the match comes from Livingston and a drilled pass from Jay Emannuel-Thomas falls perfectly for Nicky Devlin, with the full-back powering a rising, first-time shot just wide of the far top corner.

Willie Miller
Former Aberdeen captain on BBC Sportsound

And we're away at Pittodrie and McDiarmid Park after a moment of remembrance for the Duke of Edinburgh.

Third-tier Clyde's schedule has been so hectic in League One, manager Danny Lennon jokes that he almost had to select himself today.

"It's been a very demanding month for the boys," he tells BBC Sportsound. "They're flinging everything at it.

"I feel the lower league teams have been treated very unfairly. You've got to take welfare into consideration.

"Today's a bonus game. The boys are getting to play in a lovely stadium and we know what challenge it possesses.

"I said to the group, you believed in Santa Claus for eight to 10 years, go and believe in yourself for 90 minutes."

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St Johnstone manager Callum Davidson tells BBC Sportsound: "It'll be a tough game. Clyde have made a lot of changes as well so it'll be interesting.

"It's a good, strong squad I've got. I've used these players in all games so I'm confident whatever team I pick.

"I've got to make sure my players are at it, that their energy is high and we put pressure on Clyde."

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Livingston manager David Martindale tells BBC Sportsound: "We've had a fantastic season and it's about not letting that fizzle away.

"Aberdeen will get a bounce from Stephen Glass and I've seen his influence from afar since Derek McInnes left.

"Getting to the League Cup final was nice and we have aspirations to get to finals all the time. If we can get through today, we have a home tie with Dundee United - then you have the Old Firm playing each other - so your chances increase."

Aberdeen manager Stephen Glass tells BBC Sportsound: "It's an assessment period in essence. It's an opportunity for us to look at everyone.

"It's an opportunity for the players to show us we'd be crazy to either let them go, not extend them, not bring them. But the overriding thing is that we find ourselves in the next round of the cup come next Saturday.

"We want to play a certain way and we've got the players to do it. It's difficult to change things drastically over three days. But I'm hoping we see a difference in the performance level today."

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Livingston made it 14 games unbeaten with their first win at Pittodrie since 2004 in early February but form has fallen off a cliff ever since, with just one league victory.

Last weekend's mauling against Celtic made it six defeats in eight Premiership outings, along with a sore League Cup final loss to St Johnstone.

Time is running out for Livi to rediscover their spark.

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This is Clyde's sixth game in 13 days, but Danny Lennon's side will look to Montrose for inspiration after their fellow League 1 part-timers gave Kilmarnock some nervous moments in the early kick off despite having had to take the field 40 hours following their 5-0 drubbing by Partick Thistle.

The Cumbernauld side suffered their own disappointment on Thursday night, a 1-0 defeat at home to Dumbarton.

Since a three-game unbeaten run after their mini-shock away to second-tier Ayr in the previous round, Clyde have lost three in a row.

Much will depend on how much energy they have left, especially with star man David Goodwillie on the bench. After a run of 10 goals in 11 games, the 32-year-old former Scotland striker has drawn a blank in the latest three.

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St Johnstone boss Callum Davidson has already bagged the League Cup and a top six Premiership finish - not too bad for his debut season as a manager.

Could he make it a cup double?

With Rangers or Celtic waiting for the winners of this one at McDiarmid Park, it's going to be tough.

Last week's defeat to Aberdeen brought a six-game unbeaten run to an end for the Perth side.

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Tom English
BBC Scotland's chief sports writer

Clyde manager Danny Lennon appears to have decided that Tuesday's crucial league game against Forfar Athletic is his priority as he makes eight changes to his side from Thursday's 1-0 defeat by Dumbarton. That left Clyde behind the Sons and into the second-bottom relegation play-off place.

Captain and talisman David Goodwillie is among those who drop to the bench.

Only defenders Marky Munro, Craig Howie and Ewan Otoo, the latter on loan from Celtic, retain their places.

Goalkeeper David Wilson, key defender Tom Lang and midfielder Barry Cuddihy, who has been in good form in recent games, miss out completely.

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As the new manager starts at Aberdeen, the man he has replaced is looking on.

Derek McInnes looks nice and relaxed on media duties.

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Craig Levein
Former Hearts manager on BBC Sportsound

St Johnstone boss Callum Davidson makes eight changes to the side that lost 1-0 to Aberdeen last Saturday, as Zander Clark, Shaun Rooney, Ali McCann, Craig Bryson, Callum Booth, Glenn Middleton, Craig Conway and Chris Kane make way.

Coming in to replace them are Elliot Parish, James Brown, Liam Craig, David Wotherspoon, Scott Tanser, Michael O'Halloran, Guy Melamed and Stevie May.

Not exactly a weak team despite the wholesale alterations.

St Johnstone: Parish, Kerr, Gordon, McCart, Brown, Craig, Wotherspoon, Tanser, O'Halloran, Melamed, May.

Substitutes: Clark, Booth, Rooney, Bryson, McCann, Gilmour, Kane, Middleton, Ferguson.

Clyde: Vajs, Thomson, McNiff, Munro, Cunningham, Howie, Jack, Otoo, Lamont, Bain, Robertson.

Substitutes: Mitchell, Love, Goodwillie, Nicoll, Rumsby, Jamieson, Butterworth, Ritchie-Hosler.

Livingston manager David Martindale resists the temptation to make sweeping changes after their 6-0 thumping away to Celtic last time out.

Max Stryjek comes into goal in place of on-loan Rangers man Robbie McCrorie.

New manager Stephen Glass makes two changes, with forwards Connor McLennan and Fraser Hornby in the starting line-up.

Florian Kamberi drops to the bench, while full-back Jack MacKenzie, who played in the cup during a loan spell with Forfar, misses out after last weekend's 1-0 win away to St Johnstone.

Clyde and Livingston will have to overcome recent Scottish Cup trends if they are to end a 16-year hoodoo and reach the quarter-finals for the first time since 2005.

The Bully Wee reached that stage after a home replay against Ross County before being hammered 5-0 by eventual winners Celtic. Livi, beaten by St Johnstone in this season's League Cup final, edged out Alloa but then lost to Hearts.

In contrast, Saints reached the quarters last season, losing to winners Celtic, and Aberdeen were beaten semi-finalists.

Livi won 2-0 at Pittodrie in February, the sides drew 0-0 in West Lothian in January, while the Dons won 2-1 at home in August, so a close encounter is likely. Meanwhile, it is Saints' first meeting with Clyde since 2009, with the Cumbernauld side last winning at McDiarmid Park 3-2 in August 2008.