As Big Sam would say, tiki-taka is bobbins. Or close, anyway.

Manchester United have been very direct tonight but they lead. Perhaps there is method to their madness.

Former Cambridge forward Steve Claridge on 5 live Sport

"Fellaini should be down the middle getting on the end of balls like that. He came in at the far post and provided aerial dominance, attacking the ball. So why on earth has he been playing wide left? I had no issues with the way Man Utd played down at Cambridge, but even now they now lead I still don't know what Van Gaal is trying to achieve with this system."

Fulham on track to book a fifth-round tie with Bradford then.

That's why Manchester United have been hitting Marouane Fellaini - because it works. He gets up high to head down a cross from Angel Di Maria and Juan Mata is in the six-yard box, sticks out a foot and pokes it in off the bar.

Image source, Reuters

BBC Sport's Simon Stone at Old Trafford: "There have been moments in the opening 25 minutes - Rojo's instant control on the touchline - when the class in United's ranks show.

"But there are many others when it appears they are making it up as they go along.

"Plenty of misplaced passes, too many players in one area, not enough in others, Wayne Rooney having to encourage Paddy McNair to make an overlapping run to give him some room. It's all oddly disjointed."

Adam in Edinburgh: For once I completely agree with Steve Claridge, LVG's tactics are nothing short of ludicrous and I now feel bad about criticising David Moyes.

Owen from London: Our tactic is to hit long balls to Fellaini? Clever to out-Cambridge Cambridge.

Barry: Luke Chadwick one more Premier League medal than Steven Gerrard...

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Angel Di Maria is fine now, putting in a cross from the left which is headed away. United's formation does have one flaw, the spare man on every attack is Paddy McNair on the right. He looks very uncomfortable out on the wing.

Problems here. Angel Di Maria slips as he clips a ball forwards and looks to go over on his ankle. That made my eyes water! But he appears to be OK after a bit of treatment.

Jamie Murphy scored twice as Sheffield United beat Swindon on Saturday, and he's on target again as Nigel Clough's side take the lead against the run of play. Murphy, who agreed a new contract over the weekend, takes on Michael Doyle's pass and strikes a low shot under keeper Thorsten Stuckmann, who probably should have saved it.

Image source, Getty Images

For all of the consternation behind Wayne Rooney playing on the right, he's still been Manchester United's busiest player. He cuts in on to his left foot and drills in a low shot which is well held by Chris Dunn.

Sunderland were excellent in the opening 15 minutes but they haven't reacted well to going behind. Jermain Defoe has been kept quiet in the last 10 minutes or so.

And Ross McCormack then whistles a shot wide from 20 yards for Fulham.

Has Angel Di Maria been a disappointment for Manchester United? Not really hit the heights of a £60m man. He scuffs a shot across the box before Marouane Fellaini wins another header but nobody can turn it in.

Manchester United are basically going long.

Sheffield United, the cup experts of League One, are having a tough time of it here, despite Marc McNulty seeing his shot deflected just wide. At the other end, Preston centre-back Tom Clarke's header from a Kevin Davies flick is well saved by keeper Mark Howard.

Wayne Rooney wins a header at the back post, from this berth on the right which has really got Steve Claridge's goat. Marouane Fellaini is basically playing up front. He'd make a good targetman in League Two.

Southend United manager Phil Brown
BBC Radio 5 live sports extra

"It wasn't a great corner, but it was put into a dangerous area and there must have been 14 or 15 bodies in the penalty area, but Fulham reacted quickest and they are one up against the run of play."

BBC Sport's Simon Stone at Old Trafford: "Those empty seats filled up as the teams came out, but plenty were only just taking them as Tom Elliott hit the post.

"A nervy start from United and their defence still looks suspect despite recent improvements."

Former Cambridge forward Steve Claridge on 5 live Sport

"What an odd, odd system from Van Gaal. What an odd way to put out a team with the players you've got. Fellaini on the left wing and Rooney on the right? Really? Does that fit?

"Why is he even out there, Rooney? Sir Alex used to play him there, but only when they were up against the likes of Bayern Munich and Real Madrid. If I was a player playing for United I would be absolutely deflated. If I was Rooney playing out wide against Cambridge, I would wonder what on earth the manager was doing with me. What am I doing out here? It's just crazy."

Entirely against the run of play, Fulham lead! Hugo Rodallega puts them ahead after Sunderland can't clear a corner, Cauley Woodrow sees his shot smothered on the line but Rodallega is there to batter in off the underside of the crossbar. That's 10 for the season for Rodallega.

Image source, AFP

Live from the side of the M6 motorway, BBC Cambridge reporter Sam Edwards, external and several dozen Cambridge fans are stranded after their transport broke down:

@edwardssport:, external One local coach company on way for pick up, here any minute. Breakdown recovery on the way. Two more coaches coming back to also help. Those coaches will take fans to Old Trafford. Hope remains to see the second half.