It's all United at the moment.

The ball is laid back into the path of Nicky Clark and the striker steers it wide of the sprawling Gary Woods but off the outside of a post.

Willie Miller
Former Scotland defender on BBC Sportsound

Aberdeen's central defence is being taken apart and former Dons defender Mark Reynolds plays a fine ball into the penalty box.

Jeando Fuchs gathers and the midfielder looks poised to extend the visitors' lead before goalkeeper Gary Woods' strong arm saves the day.

So close to a second for United.

Scorer Marc McNulty fires a low cross across the face of the six yard box and midfielder Ian Harkes is a whisker away from a touch before crashing painfully into the far post.

Willie Miller
Former Scotland defender on BBC Sportsound

United take the lead after their two Scotland strikers combine.

Lawrence Shankland finds Marc McNulty in space and the ball is despatched low and calmly into the far corner from 15 yards.

Image source, BBC Sport

Almost a calamity for Aberdeen's defence.

Jonny Hayes delays his clearance just inside the home penalty box, he is closed down by Marc McNulty and the ball deflects off the striker and powerfully towards goal.

Fortunately for Hayes, goalkeeper Gary Woods is on hand to prevent the goal.

Craig Levein
Former Dundee United manager on BBC Sportsound

So close to the opener!

Matty Kennedy unleashes a shot from the edge of the penalty box and, when Deniz Mehmet parries clear, Callum Hendry strikes the prone goalkeeper with his shot on the rebound.

Lewis Ferguson heads over the crossbar from the resulting corner.

Aberdeen have the first good sight at goal as Jonny Hayes plays a dangerous low cross into the visiting penalty box.

Callum Hendry has his back to goal and, with the easy option to play it back into the path of the unmarked Lewis Ferguson, the on-loan St Johnstone striker shot high over the crossbar on the turn.

United's first foray into the Dons penalty box ends when Scotland striker Lawrence Shankland loses control with only defender Tommie Hoban to beat following a quick pass from Marc McNulty.

It's been a subdued start, but Aberdeen have had the territorial advantage so far.

United get the game under way, after a peep from Kevin Clancy's whistle, in their purple change strip and with Aberdeen in their traditional all red.

Aberdeen manager Stephen Glass tells BBC Scotland: "I think we're already seeing that the players are responding to what we want them to do.

"The pressure that this club brings is the sort of pressure that you want in your working life.

"I think to be a success at Aberdeen you have to put a trophy in the cabinet."

Here come the teams into the north-eastern sunshine at Pittodrie...

St Johnstone in 2014 are the last of today's teams to have won the famous Scottish Cup trophy.

Four years earlier, Dundee United triumphed - and 2009 was Rangers' last victory in the final.

You have to go back to 1990 for Aberdeen's last win in the tournament.

Hibs, who are the first team through to the semi-finals, won the cup in 2016.

Kilmarnock meet St Mirren in Monday's live BBC TV match and those sides last claimed the trophy in 1997 and 1987 respectively.

Celtic have lifted the cup four years running. But, after they were knocked out last week by Rangers, there will be a new name on the cup this season.

Image source, SNS

Dundee United manager Micky Mellon tells Sportsound: "We're looking forward to a great game in fantastic conditions.

"I'm probably expecting it to be tight again.

"We've had good games of football against Aberdeen over the course of the season."

Aberdeen manager Stephen Glass has promised to give youth a chance and has two players still to make their debut on the bench.

Tom Ritchie has joined captain Joe Lewis as one of two goalkeepers among the substitutes and is joined there by 20-year-old Mark Gallagher.

Gallagher's fellow midfielder, 17-year-old Ryan Duncan could make his second Dons appearance.

Image source, SNS

Tyrone Smith
BBC Scotland at Pittodrie Stadium

There has been little between Aberdeen and Dundee United in the three Premiership encounters the pair have contested this term.

So it would come as no great surprise if this afternoon’s quarter-final goes the distance to determine who is going through.

Aberdeen are looking to take another step towards ending their 31-year wait to get their hands on the trophy and they have cause to be cautiously optimistic as they prepare to take to the field against United.

As well as having home advantage, there have been clear signs of improvement during the short time new manager Stephen Glass has been at the helm.

But United will be feeling optimistic too - and not just because they have had slightly the upper hand over the Dons this season.

After coming up from the Championship, the Tangerines have more than comfortably secured their top-division status and will feel pretty good about themselves as they look to try to progress in the competition.

United have not won at Pittodrie in four visits since August 2014 and the striking department could decide whether that continues.

It remains a conundrum for both managers. In his two games in charge after quarantine, Aberdeen's Stephen Glass has rotated four strikers and it was left to midfielder Lewis Ferguson to be the main midweek threat - and scorer.

Micky Mellon, meanwhile, continues to struggle to get the best out of Scotland duo Lawrence Shankland and Marc McNulty along with Nicky Clark, but at least all three have found the net in a run of four consecutive wins that ended with midweek defeat away to Kilmarnock.

All three return today after being rested in a 3-0 loss by Kilmarnock that can probably be viewed as a blip considering Mellon made seven changes to his side.