Postpublished at 71 mins
Dundee United 0-2 Celtic
Dundee united throw on the youngsters. Miller Thomson, 17, and Archie Meekison, 19, get their chance.
Marc McNulty and Dylan Levitt make way.
Celtic v Rangers & Hearts v Hibernian in Scottish Cup semi-finals
Callum McGregor's low drive skids off Nicky Clark and into the net; Daizen Maeda's cross is dropped by Benjamin Siegrist for Giorgios Giakoumakis to tap in
Giakoumakis diverts Karamoko Dembele's deflected cross in off far post
Hearts, Hibernian & Rangers already through to semi-final
Andrew Southwick
Dundee United 0-2 Celtic
Dundee united throw on the youngsters. Miller Thomson, 17, and Archie Meekison, 19, get their chance.
Marc McNulty and Dylan Levitt make way.
Dundee United 0-2 Celtic
Celtic are beginning to stretch Dundee United and Greg Taylor has a hit from just outside the area, but it's straight at the goalkeeper.
Dundee United 0-2 Celtic
Adrian Sporle is brought on for Dundee United in place of Kieran Freeman as manager Tam Courts rolls the dice.
Dundee United 0-2 Celtic
Pat Bonner
Former Celtic goalkeeper on BBC Sportsound
Quote MessageThe number of mistakes that have been made during this game. Now the keeper does that for United, that's his bread and butter coming in at his chest. It's error after error, is it the ball? There has to be some reason for it!
Dundee United 0-2 Celtic
Craig Levein
Former Scotland manager on BBC Sportsound
Quote MessageWe must credit Giorgos Giakoumakis for following in at what looked like a simple save. He was the only player on the field who had that thought.
Dundee United 0-1 Celtic
Dundee United, who were beginning to look like they could make a game of it, have their heads down after that second goal, and Daizen Maeda makes a another run into the box, but his cut-back is poor and United get off with one.
Giorgos Giakoumakis
Oh dear, it's a horror moment from Dundee United goalkeeper Benjamin Siegrist that may well end their cup hopes.
A weak cross from Daizen Maeda should be an easy collection for Siegrist, but he lets it slips through his hands, and Giorgos Giakoumakis has a simple tap in.
Dundee United's Ilmari Niskanen is yellow carded for a foul on Josip Juranovic.
Dundee United 0-1 Celtic
Craig Levein
Former Scotland manager on BBC Sportsound
Quote MessageIf Dundee United were even 50% capable of doing the right thing in the final third, then there's a chance there for them to get back into this. Celtic are poor at the back and a bit slack in an attacking sense too. Dundee United are making it worse for themselves with their own ineptitude.
Dundee United 0-1 Celtic
Best spell of the game for Dundee United so far as they continue to come forward at pace, but they can't get that final ball right and Celtic goalkeeper Joe Hart still has yet to make a save.
Dundee United 0-1 Celtic
Celtic defender Cameron Carter-Vickers makes a nervy clearance under pressure, and itfalls to Ilmari Niskanen who drives forwards, feeds Marc McNulty, and his low cross is just deflected away from a United boot.
Should Niskanen or McNulty just have taken the shot on though?
Dundee United 0-1 Celtic
Craig Levein
Former Scotland manager on BBC Sportsound
Quote MessageI honestly cannot remember an occasion where either striker has held the ball up for Dundee United.
Dundee United 0-1 Celtic
Celtic's Matt O'Riley takes aim with the free-kick but it's low, lacks power, and goalkeeper Benjamin Siegrist makes a simple enough save.
Dundee United 0-1 Celtic
Callum Butcher trips Giorgos Giakoumakis right on the edge of the box.
It's a yellow card to the Dundee United man and a dangerous free-kick for the hosts to defend.
Dundee United 0-1 Celtic
The second half is underway, and Celtic have made a half-time change before the restart - with Tom Rogic replacing Reo Hatate, who was on a yellow card.
HT: Dundee United 0-1 Celtic
Tyrone Smith
BBC Scotland
Celtic with the lead at Tannadice, and a deserved one too. They've dominated for large spells, certainly in terms of possession anyway. United have offered little in terms of attacking threat, but the big positive for the home side is that they are still very much in this tie.
That will be what Tam Courts is hammering home to his side at the break, while his Celtic counterpart will be urging his side to turn their dominance in goals after the interval.
HT: Dundee United 0-1 Celtic
Craig Levein
Former Scotland manager on BBC Sportsound
Quote MessageTam Courts won't be too despondent. Their work in Celtic's last third has been poor but they've brought to the match the effort that is required.
HT: Dundee United 0-1 Celtic
Pat Bonner
Former Celtic goalkeeper on BBC Sportsound
Quote MessageAnge Postecoglou will be delighted to get the first goal in this cup tie, it is always crucial. Dundee United have got to do a few things differently in the second half to get back into it.
Celtic lead at half-time through Callum McGregor's strike, which took a wicked deflection off of Marc McNulty to take it past goalkeeper Benjamin Siegrist.
After that, there hasn't been too many chances. Celtic did have the ball in the net again but handball against Giorgos Giakoumakis ruled that one out.
At the other end, Dundee United's best chance has been a Ryan Edwards shot over the bar and the home side need to show more if they are to keep their cup dreams alive.
Dundee United 0-1 Celtic
The last action of the first half is a Celtic corner. There's a half-hearted appeal for a penalty after the ball hits the arm of a United defender, but his hand was fully against his body.