Scottish Cup: Aberdeen v Dundee United - pressure all on Stephen Glass' side

The fourth 'New Firm' derby of the season is the biggest in years as Aberdeen and Dundee United compete for a place in the Scottish Cup semi-finals.

It's always a key contest when these clubs go head to head, but Sunday's showdown brings extra significance.

Having played in the fixture for both sides, I know just how much it would mean for either to go on and lift the silverware.

And with half of the Old Firm already out the way after Rangers defeated Celtic, there's a greater opportunity for Aberdeen or United to fulfil that dream.

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Aberdeen look to shed nearly men tag

The Scottish Cup could be pivotal for both of them. Each have a manager in his first season in charge - in Aberdeen's case his first fortnight - and winning the trophy would be a landmark triumph that could spur the club on to the next level.

There's more pressure on Aberdeen to deliver this weekend. Dundee United are a great club, steeped in tradition, and more than capable of victory at Pittodrie.

But they approach the tie under less strain, even though they'll be desperate to win it, as will their fans. Their objective this season was to stay in the Premiership, not become a yo-yo team, and they've done that.

They've come up and re-established themselves in the top flight. In fact, they've probably exceeded expectation because they've comfortably stayed clear of the relegation battle.

It's been 11 years since United last won silverware, the Scottish Cup under Peter Houston, and matching that success would be an incredible achievement.

Aberdeen haven't had to wait as long for a trophy as they were League Cup winners in 2014 during Derek McInnes' tenure.

Their Scottish Cup hoodoo, though, stretches to 31 years. It's hard to win trophies when you've got the Old Firm there but they would have wanted more. They've had decent runs - runners-up in 2017 and semi-finalists in each of the last three seasons - but the next step is winning.

Quiet, unassuming Glass has inner steel

Billy Dodds and Stephen Glass were part of Aberdeen's 1995 League Cup-winning team

Stephen Glass has definitely grown into the role of manager. When I played with him at Aberdeen he was such a nice boy, a great lad. He had the drive but was very quiet and unassuming.

Did I see him becoming a manager? Not at all. But I know how driven he is. I know he's been at Atlanta United but to get Aberdeen as your first big job in Europe is an unbelievable opportunity for him.

A lot of people are looking at Glass and judging him on where Aberdeen have been as a club and what McInnes did, so he's got to start well. Beating Livingston to reach the quarter-final, and taking a Premiership point against Celtic, the early signs are promising.

Having helped the club to 1995 League Cup success, Glass is already a hero for Aberdeen but he'll be an even bigger one if he steers them to Scottish Cup glory.

Will Mellon's protection strategy pay off?

With this tie looming, each manager took a different approach to preparation in midweek.

Glass went strong by putting out his best available side in the draw with Celtic, while Micky Mellon made seven changes as his side slumped 3-0 at Kilmarnock.

Because they've achieved their objective of staying in the league, Mellon can do what he wants with his team selection, it's not about what the players think. They all want to play, but you have to take it out of their hands.

I don't blame him at all for keeping things fresh for the Scottish Cup. Wednesday night wasn't the most important game, the priority is this tie.

I wouldn't be surprised if the game mirrors Aberdeen's tie against Livingston last weekend and goes to extra time and penalties.

Aberdeen have the better squad but haven't shown it enough this season. United have players such as Lawrence Shankland and Marc McNulty who can hurt the hosts. A compelling contest awaits.

Billy Dodds was speaking to BBC Scotland's Matthew Reed

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