Live coverage on BBC One Scotland's Sportscene has started, with pundits Michael Stewart and Peter Lovenkrands joining host Steven Thompson.

Image source, BBC Sport

Seven-time cup winners Dons reached the semis last term and were beaten finalists in 2017 but have not lifted the trophy since 1990, while United have made the final once - in 2014 - since lifting the cup for a second time in 2010.

Aberdeen were a couple of seconds away from securing their place in the European Conference League before Leigh Griffiths equalised for Celtic on Wednesday, but with fifth-top Livingston losing to Hibs, that will surely only be delayed.

His side nevertheless unbeaten in four outings since losing to United 1-0 at Tannadice, it is no surprise that new manager Stephen Glass is now targeting cup glory.

United came from behind to beat Partick Thistle 2-1 in round three.

And, in round four, Peter Pawlett scored the only goal in the 1-0 victory away to another League 1 side, Forfar Athletic.

Image source, SNS

Callum Hendry's late goal secured Aberdeen a 1-0 win away to Dumbarton in thethird round before a dramatic fourth-round meeting with Premiership rivals Livingston.

The Dons twice came back from Jay Emmanuel-Thomas goals, with Niall McGinn and Florian Kamberi on target for the hosts.

After extra-time, Stephen Glass' side prevailed 5-3 on penalties.

Image source, SNS

It may be unwise to expect a lot of goals at Pittodrie this afternoon as there has only been one between Aberdeen and Dundee United so far this season.

That was scored by Adrian Sporle, who misses out today, in United's 1-0 win at Tannadice in March, which followed 0-0 draws in January and October.

Image source, SNS

Aberdeen were on course for a rare win over Celtic on Wednesday after Lewis Ferguson put them ahead, but Leigh Griffiths intervened late on to secure a draw in Wednesday's Premiership encounter.

Coverage of today's two quarter-finals is about to start on BBC Radio Scotland's Sportsound.

Among the pundits are former Aberdeen and defender Willie Miller, former Dundee United boss Craig Levein, former Rangers midfielder Charlie Adam and ex-Motherwell boss Stephen Robinson.

Image source, SNS

United would have wanted a better performance to take into today's match. The Tangerines were beaten 3-0 as Kilmarnock's Kyle Lafferty knocked in a Premiership hat-trick on Wednesday.

However, manager Micky Mellon had made seven changes for the game and his main men will return today.

Speaking to BBC Scotland, new Aberdeen manager Stephen Glass insists he will only be considered a success at Pittodrie if he delivers a trophy.

As expected, Dundee United are much changed from the side that lost 3-0 to Kilmarnock on Wednesday, with manager Micky Mellon having rested several first-choice players.

Ryan Edwards and Mark Reynolds are restored at centre-half, with Calum Butcher returning to the midfield. And, up front, Marc McNulty, Nicky Clark and Lawrence Shankland all start.

Kerr Smith, Mark Connolly, Luke Bolton and Louis Appere drop to the bench, while Florent Hoti and Adrian Sporle miss out.

As already mentioned, loan signing from Celtic Ross Doohan is on the bench with Deniz Mehmet again deputising in goal for the injured Benjamin Siegrist, who is awaiting the results of a scan on his wrist.

Image source, SNS

Aberdeen: Woods, Hayes, Considine, Hoban, Ramsay, Ferguson, Campbell, Kennedy, McGinn, Hendry, Kamberi.

Substitutes: Lewis, Ritchie, Hornby, McGeouch, McLennan, Ross, Gallagher, Ruth, Duncan.

Dundee United: Deniz, L Smith, Edwards, Reynolds, Robson, Harkes, Butcher, Fuchs, McNulty, Clark, Shankland.

Substitutes: Doohan, Connolly, Pawlett, Chalmers, Bolton, Appere, Davidson, Watson, K Smith.

Dundee United signed Celtic goalkeeper Ross Doohan on an emergency loan on Saturday with first choice Benjamin Siegrist likely to be out for the rest of the season and Jack Newman also unavailable.

Deniz Mehmet deputised for Siegrist during the week in the loss to Kilmarnock and continues this afternon.

The 23-year-old Doohan started the season with Ross County, making five appearances for the Premiership side having had previous loan spells with Greenock Morton and Ayr United, and is named n the bench.

Image source, SNS

Aberdeen are early with their team details and the big news is that goalkeeper Joe Lewis is fit again after missing out in midweek against Celtic with a rib injury, but manager Stephen Glass names him on the bench and keeps faith with Gary Woods.

Ross McCrorie had to go off against Celtic with an ankle injury and misses out today, meaning the only change to the starting line-up is 17-year-old Calvin Ramsay taking his place at right-back.

Image source, SNS

There were goals, a dramatic comeback and a penalty shootout at Easter Road last night, with Hibs prevailing against Motherwell to reach their seventh Scottish Cup semi-final in 10 years.

Indeed, the Leith side have now reached four domestic cup semi-finals in a row.

You can read the match report here and watch the highlights below.

After last night's thrilling quarter-final at Easter Road, where Hibernian defeated Motherwell on penalties, there are two more Scottish Cup ties featuring top-flight sides today, starting with our first BBC TV live game of the round at Pittodrie (14:30 BST).

Aberdeen entertain east coast rivals Dundee United and you can watch, listen and follow text coverage of the match.

Later, at 18:30, Rangers and St Johnstone meet for the second time in four days after drawing on league business during the week.

Let's get to it.

Image source, SNS