Are we about to see another shock at Millwall? The Championship side are throwing players forward in search of an equaliser.

There are 32 places between them and third tier Rochdale, who have really impressed today.

Here comes Saints' new £19m striker Guido Carrillo.

Seven minutes for him to making a scoring start to life in English football.

Image source, Getty Images

It should be....it isn't!

Oh dear. Lukas Jutkiewicz should be sealing Birmingham's place in the fifth round but he allows Terriers goalkeeper Joel Coleman to make a fantastic save.

Coleman should have been a spectator with a close-up view of the winner there though.

Ten to go.

Image source, PA

That's another really smart save from Coventry keeper Lee Burge - he reacted quickly to tip over Marcus Tavernier's deflected looping shot.

The home side are pressing hard for an equaliser here... right now it's the League Two team who are going through.

Notts County are starting to tire now and Jordan Ayew tries his luck from long range but it's straight at the keeper.

10 minutes to go at Meadow Lane.

Tony Pulis is giving it the full tic-tac-man-at-a-race-track on the sideline, trying to wring a winner out of his Middlesbrough side.

Leon Osman
Former Everton midfielder on Final Score

We're not sure if the ball went out in the build up to the goal, but let's not take anything from Notts County and from John Stead. He's scored in every round and scored in his last six matches.

Only Sergio Aguero (8) has scored more goals in 2018 than Jon Stead (6) in England's top four divisions.

Jose Heriberto Izquierdo, on as a substitute, swivels nicely in the box, but his snapped shot is straight at Middlesbrough goalkeeper Darren Randolph.

Image source, Reuters

A decent effort for Preston as Daniel Johnson darts a powerful shot just wide of the post - still the away side haven't had a shot on target.

Chris Waddle
Ex-England winger for Radio 5 live at Meadow Lane

Swansea have had a good reaction to the Notts County goal, they've stepped up their game, and have asked a lot of questions of the County defence. But so far, County have defended well.

David Marshall to the rescue for Hull.

The former Cardiff stopper stretches back to tip Joe Worrall's header over the bar.

And then Forest hit the post!

Ben Brereton's little near-post nudge trickles across goal and rebounds to safety off the far stick.

So close. Fifteen to go.

Sterling work from Coventry's goalscorer Maxime Biamou once more as he zooms up the pitch and bags his side a free-kick. That will take the pressure off - for some time at least. MK Dons are pushing hard.

Adama Traore is still bustling and hustling.

The Middlesbrough winger lets fly from 20 yards and skims the wrong side of the side netting from the home fans' point of view.

Any goal now is likely to be a knock-out blow.

Middlesbrough summoned Stewart Downing and Brit Assombalonga off the bench in the first half.

Time for Chris Hughton to reach for his (relatively) big guns. Glenn Murray is on for Tomer Hemed.

Jordan Ayew comes on for Tammy Abraham.

20 minutes to go at Meadow Lane and all still to play for.

A big clash between Daniel Johnson and Sheffield United's John Fleck sees the Preston man booked.

This really has not been a classic in terms of chances.

Leon Osman
Former Everton midfielder on Final Score

It will be argued about and discussed.

Will Grigg is only a yard from Reece Burke when he kicks the ball and there's a slight movement of the arm, but it's tucked into his body.

Birmingham's Jota slots away from a left-wing delivery, but he is well offside and the linesman's flag is up as hot as a freshly toasted pop tart.

Phil Brown
Former Southend manager on BBC Radio 5 live sports extra

It's been a disastrous day for West Ham, it's 2-0 and it could end up three or four.

Will Grigg puts the penalty straight down the middle, he's on a hat-trick now and it wouldn't surprise me if he gets it. It's not been how you expect a West Ham team to play, or a David Moyes team.