|Scottish League Cup final: Dundee United v Celtic|
|Venue: Hampden Date: 15 March Kick-off: 15:00 GMT|
|Coverage: Live on BBC One Scotland from 14:40 GMT, BBC Radio Scotland FM, MW and digital from 14:05 GMT and BBC Sport website|
Amidst the aggression, the controversy and a case of mistaken identity, a moment of technical aplomb flourished.
Stefan Johansen's expertly crafted ball into the Dundee United penalty area allowed Leigh Griffiths to equalise last weekend at Tannadice, and it was a typical piece of composure and guile.
Johansen is increasingly coming to embody this Celtic team. His energy and industry is relentless, but the worth of his game cannot be reduced to sheer effort alone.
He is a restless figure, yet covers the ground with an elegant grace.
The contradictions continue, since the slight frame belies a near limitless stamina, and the modest personality belongs to a player who is integral to the best of Celtic's play.
Ronny Deila's admiration for the Norwegian international is evident, since he is seldom rested and has been moved to a position in the team that sets the tone, the rhythm and the intensity of Celtic's approach.
In that respect, Johansen is a pivotal figure for Deila's side. Only Anthony Stokes, Steven Lawless and Marley Watkins have more than his six assists in the Premiership this season, while he has also contributed five goals.
The influence is especially marked since Johansen earned his reputation under Deila at Stromsgodset as one of the two deep-lying midfielders, yet now plays in the attacking midfield role that Celtic build their play around.
In a similar respect, albeit with a different sphere of influence, Paul Paton is a vital player for Dundee United. He is tigerish in the centre of midfield, carrying out an important role in breaking up the play of opponents.
He performs with a fierce spirit, a squat and energetic presence in the ballast of United's midfield, working behind the front four so that they have greater licence to roam.
Johansen and Paton are, in their own ways, symbolic of their teams.
Prior to the transfer window, Stuart Armstrong was the critical midfielder at Tannadice. A young, developing attacking midfielder - full of graceful running and incisive passing - but he is now working alongside Johansen at Celtic and offers an alternative in the central attacking midfield role if Deila wants to move the Norwegian into different areas of the field.
United still strive to be progressive, and the likes of Charlie Telfer, Ryan Dow, Chris Erskine and Blair Spittal have provided alternatives to the loss of imagination and running menace since Armstrong and Gary Mackay-Steven left for Celtic in January.
For now, though, it is the resilience of United that matters, the sense that when the side is hard-edged and dynamic that it can still be a match for the teams above them in the Premiership.
They opened the scoring against Celtic in the Scottish Cup quarter-final, after both sides had been reduced to 10 men, and held on even when they had been reduced to nine men and Celtic had equalised through Griffiths. That bloody-mindedness survived Paton's early dismissal, when the assistant referee wrongly identified him as the miscreant in a tussle with Virgil van Dijk, when instead it was his teammate Calum Butcher.
It has been a season of further progress for Paton, though, and United seldom line up without his qualities in the driving heart of the team.
At 27, and also now an international footballer with Northern Ireland, he has established himself as a top-flight player and his qualities will be vital to United if they are to overcome the odds at Hampden in the League Cup final.
He is unlikely to man-mark Johansen, but operate in the same areas of the field. The task of following the Norwegian around would stretch the limits of endurance as well as the defensive attributes of any marker.
Johansen was once a player of potential but no purpose. That altered when he arrived at Stromsgodset and began to work with Deila, and their relationship has become a central aspect of the manager's reign at Celtic Park.
Deila wants his side to play with energy, pressing opponents relentlessly and then using the ball carefully but effectively when they win it back. Johansen embodies all of these qualities, and there are few candidates who might effectively challenge him to be Scottish football's player of the year.
Upright, alert, conscientious and technically adept, he is the archetypal modern footballer.
"When you come to a club like this, you need to know the pressure you have," he said.
"You have pressure as a player and as a team. You just get more grown up. It's more physical than I was used to in Norway and you need to adapt to that.
"I played some games under [Deila at Stromsgodset] in that [attacking midfield] position, but most of the time as a holding midfielder. It's just a positive to be able to play in two positions.
"[I've never scored] as many goals before. In that position, it's important to help the team with assists and goals, that's a responsibility you need to accept."
Celtic are pursuing the treble, while United are seeking a comparatively rare cup victory. There are strengths and weaknesses to both teams, and a gap in resources and strength in depth that firmly favours Deila's side.
In Johansen, they also are likely to have the most assured and effective player of the pitch. And yet Paton, in his scurrying effort, will seek to reduce his opponent's impact and allow United's more creative players to have an impact on the game.
It will not be a private battle, but in their proximity to each other, they will be worth watching.