Dundee also make a change, Yan Dhanda off for Joe Bevan.

Young Colby Donovan is coming on for Celtic, replacing Julian Araujo.

Celtic go into the break in extra time with the lead thanks to Sebastian Tounekti's finish.

This game has flipped. Now Dundee need to find something.

Image source, SNS

Dundee are just getting their foot on the ball a bit again.

This is going to take an almighty effort to get back level, but they've got time.

Rory Loy
Former Dundee striker on BBC Sportsound

If you're some of the guys in the Dundee team who have worked all game, it's very difficult to get yourself up for it when you were seconds away from going through.

It should be three, but Jon McCracken denies Benjamin Nygren with his boot.

The close-range finish was right at the Dundee keeper.

Dundee look gubbed.

Only feels like two minutes ago they were on their way to a famous win, now they can't get out their half.

Marcelo Saracchi forces the keeper to save at his near post, then Luke McCowan has a goal-bound shot blocked.

Martin O'Neill's name is now ringing out around Celtic Park.

Rory Loy
Former Dundee striker on BBC Sportsound

Tounekti's made a difference since he's come on, that's a goal and an assist now. Really good goal.

Image source, SNS

Away we go again.

Michael Stewart
Former Scotland midfielder on Premier Sports

Great finish from Adamu, you have to say.

It was cute.

Rory Loy
Former Dundee striker on BBC Sportsound

There's not many that thought Celtic had that in them today. You've got to feel for Dundee, but you've got to keep going until the last kick.

But they need to pick themselves back up because there's another half an hour to come.

With the last touch of normal time, Junior Adamu sends this to extra time.

Image source, SNS

Not for long, though. Dundee defend and defend and defend again.

They've been outstanding.

The Dundee defence double up on James Forrest and come away with the ball, but Celtic have possession back.

Cameron Congreve wins a free-kick on the right and the clock continues to run down.

Two minutes of the added five to play.

Five minutes added. We've played two of them already.

Kieran Tierney is thankfully back up but he'll have to make way for Marcelo Saracchi.