The first chance of the afternoon in Perth goes to the hosts, but Jamie Gullan's snapshot is well over the bar.

Shayden Morris has shown his searing pace twice now down the left-hand side for Aberdeen, but Morton have managed to stop the crosses coming in.

Tomas Bent Magnusson's first Hearts start is marked with a yellow card as he takes out St Mirren captain Mark O'Hara in midfield.

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Scotland head coach Steve Clarke and Scottish FA chief executive are in attendance at St Mirren v Hearts.

Clarke will soon name his squad for next month's opening World Cup qualifiers, while Maxwell is a former St Mirren player.

Who could he be watching? Scotland internationals Lawrence Shankland, Zander Clark and Stuart Findlay are all in action.

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Aberdeen started on the front foot, Kusini Yengi throwing in a couple of stepovers and winning a corner down the left. Morton defend the set piece though.

A healthy Aberdeen crowd is watching on at Cappielow.

Will they see a first Dons win of the season?

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Away we go around the country.

Cup drama, and plenty of it, please.

Later today. It takes place following Rangers' match with Alloa, which kicks off at 17:45 BST.

The last-eight ties are due to be played on the weekend of 20/21 September.

An intriguing all-Championship affair takes place at Firhill as former Celtic team-mates Mark Wilson and Scott Brown go head to head.

After a turbulent pre-season, Partick Thistle sailed through their group in style with four straight wins, but they were brought crashing back down to earth with a 5-1 league defeat at St Johnstone and followed that up with a 1-1 draw against Morton.

Ayr, meanwhile, also have just one point from their opening two Championship games after a draw at Arbroath and defeat at home to Raith.

This tie gives one of these teams the chance to really ignite their campaign.

St Mirren manager Stephen Robinson tells BBC Sportsound: "All in all, there's lots to be better on. We're looking for a big improvement today, which we'll need because we're playing against a very good Hearts side.

"You look at Hearts' squad and they should be up there challenging, they should be one of the top clubs in the league. Certainly we respect them but certainly we don't fear them.

"We know what we're good at. We are a very hard team to play against. We've got a lot more quality than people give us credit for."

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Andy Burke
BBC Sport Scotland at Cappielow

Clearly the resident DJ at Cappielow was at one of the mega Oasis gigs in Edinburgh last week because we are being treated to a string of the Gallagher brothers’ classics as we count down to kick-off. No complaints here.

Look up "potential banana skin" in the dictionary and this is the fixture you’ll find. With Aberdeen’s poor start to the season, you can imagine the Dons fans who have travelled here to Greenock did so with a little trepidation.

I spoke to a Morton fan on the way into the ground who was giving me a potted history of Morton's cup successes against Aberdeen down the years.

Will we see another cup shock today?

Greenock Morton manager Dougie Imrie tells BBC Scotland: "It's a great tie to look forward to, it's a chance for us against a very good team. Being at home gives us that impetus, but we've got to give them respect, they're the Scottish Cup holders.

"They won't enjoy coming down to Cappielow, the changing rooms are very small, very dark ,so we have to use all of that to our advantage - but we know it will be a difficult day today against a very good team."

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Motherwell manager Jens Berthel Askou tells BBC Scotland: "It's a big game for us to see if we can progress in the cup.

"We used [the group games] in the summer to grow as a team and now we are in the knockout stages.

"[St Johnstone] have done well at the start of the season so I expect a difficult game - we will need to be at our best. It's two teams with momentum and confidence."

On Lennon Miller's departure: "We have done well in trying to build the new team without Lennon and it looks good so far. I expect it to get better and better."

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Hearts manager Derek McInnes tells BBC Scotland: "You could make a case for so many players at the minute. It's a tough ask to pick the starting XI and the bench, to be honest. We feel this is the right team for today and hopefully it is.

"I think we're stronger in most areas. We've got to make sure we're strong against St Mirren. If we can win that middle area, we can make it the type of game we want it to be.

"It is a cup tie. At times, we're going to have to fight for every inch out there and having that physicality is always important against St Mirren.

"It's a tough tie for both of us. You have to beat good teams if you're going to progress."

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Aberdeen manager Jimmy Thelin tells BBC Scotland: "I'm looking forward to it a lot, I really like these cup games. There is always a lot of excitement and emotion and hope, so we are ready for a strong fight.

"The performances have been okay, not the results. We have to do better in the way we are attacking the opponent. We have to create more chances.

"It's what we've been working on this week and I hope we can see some signals we are improving with this squad.

"It is important to win to get through, but also for the [Europa League] play-off. We have to take some steps now on the pitch."

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St Johnstone manager Simo Valakari tells BBC Scotland: "We have a strong team out there - good to get Morgan Boyes back. As I said all week, we are playing an interesting team with a new identity.

"Our preparation is our confidence. We are confident but, as always, we are humble. We like to test ourselves against a Premiership opponent.

"Every match we want to be successful. We need to be brave with our things and take the handbrake off."

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Brian McLauchlin
BBC Scotland at Smisa Stadium, Paisley

It’s been a big week for St Mirren with manager Stephen Robinson committing his future until the summer of 2028.

And the Northern Irishman will be keen to see a better performance from his team today after last weekend's goalless draw against Motherwell.

But they take on a Hearts team who have been one of the stories of the season so far, with five new recruits in the starting XI for Derek McInnes' side.

This match has all the prospects of going to extra-time and maybe even penalties, as was the case in the Scottish Cup last year.

The holders booked their place in the last eight after a convincing four-goal win over fellow top-flight side Falkirk.

Goals from Daizen Maeda, Alistair Johnston, Dane Murray and a Liam Henderson own goal put Celtic 4-0 up before Keelan Adams pulled one back.

You can read the match report for that one here.

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Tyrone Smith
BBC Scotland at McDiarmid Park

St Johnstone knocked Motherwell out of the Scottish Cup in January. So much has changed for both clubs since then.

Premiership Motherwell have changed manager (twice!) and St Johnstone have been relegated to the Championship.

However, both teams appear to be in a much better place at the moment.

Saints have won six out of six games in all competitions, while the early stages of new boss Jens Berthel Askou’s Fir Park tenure have been very encouraging.

So this afternoon’s McDiarmid Park encounter ticks the intriguing box. And while the Premiership visitors may start as slight favourites, it would be foolhardy to confidently predict which side will progress through to the quarters.

Thistle manager Mark Wilson makes two changes as he welcomes fellow Championship title hopefuls Ayr United for some League Cup action.

Cammy Logan and Luke McBeth drop out, with Ben McPherson and Tsoanelo Lets'osa coming in.

Scott Brown makes a trio of changes for Ayr.

Shaun Want, Dom Thomas and Stuart Bannigan all come into the side, with Marco Rus dropping to the bench, while Scott McMann and Ethan Walker drop out

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