Ander Herrera gets a run out, replacing Angel Di Maria in the Manchester United midfield.

FIVE MINUTES added on. Can Fulham find an equaliser?

Former Cambridge forward Steve Claridge on 5 live Sport

"Manchester United were simply unable to unlock Cambridge in the first fixture, but here the game opened up after United scored their first goal, which completely changed the complexion of the tie."

Nice from Juan Mata, a smart backheel to find Angel Di Maria 25 yards out, and his drive is powerful and well turned over by Chris Dunn. Excellent save.

Robin van Persie is replaced by James Wilson and the Dutchman makes his way down to the tunnel, applauding the crowd on his way. An injury concern?

Preston looking comfortable as they head towards victory at Bramall Lane. Paul Gallagher has had a couple of sights of goal as he chases a hat-trick, whizzing one shot over the bar and rolling another wide. Sheffield United may have lost just two of their last 17 FA Cup ties, but they've only three minutes to save this one.

Liam McLaughlin: It's going to be a long 10mins - come on Preston!

Joe Wilkinson: I had pretty much written them off at half-time, but Preston got in the dressing room, got their heads together and started to believe.

Will Rawlinson: Joe Garner will absolutely tear up this Manchester United defence!

Get in touch on Twitter using #bbcfacup,, external text us on 81111 (UK only), or leave a message on the BBC Sport Facebook, external or Google+ page., external

And that is an excellent stop from Chris Dunn. Down to his left to push out Robin van Persie's smart shot on the turn.

Image source, AP

It's been a longer journey than Bilbo's Hobbit adventure, which spanned three Hollywood blockbusters...

@edwardssport:, external WE'RE HERE!!!

All of 40 minutes left to enjoy.

A stunning 10-minute spell from Preston has put North End on the brink of a massive cup tie with Manchester United. Can Sheffield United rally in the late stages?

About 10 minutes left.

Angel Di Maria whips in a bullet of a shot, gem of a hit, but it is brilliantly and bravely blocked by Josh Coulson. For those Cambridge fans making their way to the ground with our reporter, it may be a bit of a damp squib when they do arrive. Not much tempo or drive to the game now.

The referee has a lengthy stoppage, during which he gets both linesman onto the pitch, and in the end he decides on two yellow cards. One for each side. What a letdown after all that.

Just over 10 minutes remaining at Craven Cottage, where it's all kicked off on the sidelines. A proper scuffle. At least 15 players involved, pick the bones out of that one...

Fifth round ties as it stands will be:

Preston v Manchester United

Bradford v Sunderland

Southend United manager Phil Brown
BBC Radio 5 live sports extra

"Ricky Alvarez was on the right wing, cut back inside on to his left foot, got a bit fortunate as the ball fell for him but he ht it with venom and it's a fantastic goal for what could be the winner."

Wayne Rooney with a cracking effort, dipping strike that forces Chris Dunn into an awkward save, can only cough it up into the mixer and Robin van Persie should really bury it. He slams it over the top though.

Alan Holden: Well done Gally! Up the Whites! #PNE

David Shaw: Are we looking at a derby in the next round of the FA Cup, Preston vs Manchester United?

Not really, David...

Sunderland have been pushing hard and now have the lead, Ricky Alvarez cutting in from the right and arrowing a left-footer into the bottom corner. He's been the best player on the pitch.

Image source, Getty Images

Former Cambridge forward Steve Claridge on 5 live Sport

"A lovely touch from everyone in Old Trafford, standing and clapping Luke Chadwick off the pitch."

Well, this is extraordinary. Preston get a penalty as Chris Humphrey is brought down, and Paul Gallagher blasts the ball into the bottom corner for his second of the game. Are Sheffield United, the cup kings, about to be vanquished?

Image source, Getty Images