Luton sub Dan Potts is the son of Steve Potts, of over 500 appearances for West Ham fame.

Finally. Nathan Jones had to sprint from the Luton changing room to make sure he saw the start of this second half. 20 minutes for that break.

Luton have made a change too. Dan Potts on for Glen Rea.

Mr Kinkladze: Wonder how many people criticizing Kepa have actually played in goal ? Watch again from his angle, Zouma blocks his view and he has a split second before the ball is past him

David Bookham: Surprised it took Luton so long to figure the way to play Chelsea is to be compact and let them play with the ball in front

They've just said on BBC One that apparently there is a "dodgy clock" in the Luton dressing room, which is why they haven't started making their way out yet. Right.

Ready for more? The teams will back out and soon we're going to have at least another 45 minutes of football from the Bridge. Can't see this finishing 2-1 myself.

Oh, and the snow is falling. Magic of the Cup.

Jimmy Floyd Hasselbaink
Former Chelsea striker on BBC One

A lot of positives for Chelsea, they started well, sharp, the ball retention was good, tempo was good. That's what you want and they got that early goal and you see the smiles and they played alright in that first half.

But here is the moment that swung the game back into the balance. Kepa with a bit of a shocker, but credit to Luton for getting themselves back into the game.

And things were looking very rosy for Chelsea when Abraham added his and his team's second...

If you're just tuning in, here are the moments that mattered in that first half...

Tammy Abraham gave the home side the lead, much to the visitors' fury, who felt two balls on the pitch should have meant it didn't count.

It looked like it was going to be a thrashing at 2-0. But against all odds we have a game on our hands.

Oh, for a second I thought Luton were about to draw level. A free-kick from the left is met by the first Luton man in the box for a header that is on target but straight to Kepa, who saves.

Chelsea threaten again. Emerson's cross is poked wide at the near post by Werner. The Blues think they should have a corner. They're not going to get one.

Karen Carney
Former England and Chelsea winger on BBC One

Luton are making it really difficult, making it compact and pushing Chelsea back.

Superb work from Mason Mount provides a superb chance for Chelsea. He turns his marker inside out down the right and then whips a fierce, curling ball through the six-yard box. Nobody gambles, though, and the delivery goes begging.

Matt: I think we should probably give Kepa a go up front. He's not really a natural goalkeeper.

Luton dig in. Chelsea have the ball in the Town box and are just looking for that extra yard to get a shot away. Ziyech can't manage it, nor can Pulisic or Abraham. Excellent defensive work from the visitors.

Karen Carney
Former England and Chelsea winger on BBC One

Luton are being braver on the ball, they changed shape, built their confidence and now at 40 minutes in are very much in this tie.

Darren: Another Kepa calamity. Surely enough is enough, he has to go sooner rather than later ! Bring Willy on at half time. As for Steve in Fife, we want less complication in the game, not more!

Colm Ross: Kepa has absolutely zero confidence, can see he's totally lost his head at Chelsea.

Chelsea's swagger has eroded somewhat. They were in complete and utter control of this game at 2-0. But Luton are posing a bit more of a challenge now.

Saying that, you can easily see the home side bagging again soon, a pointy underlined as Abraham goes close to a hat-trick, with a good dart to the six-yard box but a fluffed finish from the delivery in.

Richard H: Why bother with Kepa at this point. Why isn't a kid from the academy getting a chance because he is clearly a lost cause.

Arjun Singh: Oh my word, Kepa is terrible

Image source, Reuters