Sheffield United, giant-slayers.

But can they knock out a team from their own league this evening?

And there you go - no sooner have I spoken, and the game has been delayed.

Kick-off is now delayed until 20:05 GMT. Which will allow the fans stuck in traffic at least the hope of making it. They could see some of the game anyway...

It's going from bad to worse for poor Sam Edwards,, external BBC Cambridgeshire's reporter who, along with dozens of U's supporters, is stranded on a broken down coach on the motorway:

@edwardssport:, external Driver's saying the problem more serious than I thought. Other coaches are coming to get us once they've dropped off. Another hour. Fans on this coach are furious.

I've not heard anything to suggest that this game will be delayed Chris. Those Cambridge fans marooned on the M6 have quite frankly had it.

Chris Williams:, external Not delaying the kick-off at Old Trafford would be criminal surely? Denying 6,000 fans a once in a lifetime opportunity!

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Image source, PA

There could yet be a late change to the FA Cup last 16, as West Ham could face expulsion if Fifa finds the club breached rules over the selection of striker Diafra Sakho.

Sakho, 25, withdrew from Senegal's Africa Cup of Nations squad with a back injury but scored 18 days later in West Ham's 1-0 FA Cup win at Bristol City.

Fifa rules state a player cannot appear for his club if he is meant to be on international duty.

World football's governing body has begun an inquiry but the Hammers "vigorously" deny any wrongdoing.

If West Ham are found guilty, Fifa could order the Football Association to overturn their victory over the League One side.

Rob Underdown:, external This year's Blackpool season ticket.

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Image source, PA

The last English manager to win the FA Cup - and the only Englishman in the last 20 years - has left his club today, as Harry Redknapp resigned from his post at QPR.

Redknapp, 67, won the Cup with Portsmouth in 2008, with Joe Royle's win with Everton in 1995 the only other win for an English manager in the Premier League era.

We reckon that Manchester United's starting XI cost £231m to put together, which incidentally is £231m more than Cambridge's. Can the zeroes be heroes?

Rob, a Manchester United fan: Hope Cambridge go 2-0 up so Van Gaal gets a clear hint that the 3-5-2 is rubbish. He probably won't get that hint, though. :(

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Former Cambridge forward Steve Claridge on 5 live Sport

"Cambridge can play here tonight in the same manner as the first leg. I expect them to line up with one up front, one just behind and two solid banks of four. They won't look to lave any space in behind, no gaps between the lines, and they will want to play in exactly the same manner as the previous game."

BBC Sport's Simon Stone at Old Trafford: "Louis van Gaal has caused a surprise by naming David De Gea in goal.

"Victor Valdes is still to play a first-team game after signing an 18-month contract and tonight looked like the perfect opportunity for his debut.

"The former Barcelona man will be on the bench again though as United look to book a fifth-round trip to Sheffield United or Preston."

Tom in Sheffield: Based on the teams they've played in the last two seasons in both cups, if Sheffield United were in the Premier League right now they would only be three points behind Leicester with a goal difference of +3 and having played an incredible 15 games fewer! Amazing.

I've no idea how you worked that out Tom but I'm happy to go with it...

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Sheffield United boss Nigel Clough, who made 10 changes for Saturday's 2-0 League One home win over Swindon, reverts to the starting line-up that ran Tottenham close in the League Cup three days earlier - only centre-back Chris Basham remains from the weekend.

Preston's 12-goal top scorer Joe Garner returns to the bench after more than two months out with a tendon injury. Boss Simon Grayson makes six changes, bringing in goalkeeper Thorsten Stuckmann and midfielder Neil Kilkenny for the cup-tied Sam Johnstone and Daniel Johnson - while recalling 37-year-old Kevin Davies, a boyhood Sheffield United fan, in attack.

Sheff Utd XI: Howard; Flynn, Basham, McEveley, Harris; Doyle; Campbell-Ryce, Scougall, Baxter, Murphy; McNulty.

Preston XI: Stuckmann; Laird, Clarke, Huntington, Woods, Wiseman; Humphrey, Brownhill, Kilkenny; Gallagher, K. Davies.

Image source, AP

Cambridge winning at Old Trafford. It's not going to happen. Not a chance. Never.

Right? Well I would have offered you enormous odds of Bradford winning at Chelsea - particularly from 2-0 down - so you never can tell.

Would a Cambridge win this evening be an even bigger shock?

Sam Edwards, BBC Cambridge sport and news reporter, is not having a good time of it, external as he tries to get up to Old Trafford in time for kick-off:

‏@edwardssport:, external Our coach now has mechanical problems. Stranded on a layby on the M6.

Our sympathies, Sam. But really, you should have left earlier.

BBC Sport's Simon Stone: "The deadline-day departure of Darren Fletcher to West Brom means that there is no-one left in the Manchester United squad who has an FA Cup winners' medal from their time at Old Trafford.

"Three United players do have one though. Robin van Persie was part of the Arsenal side that defeated United on penalties at the Millennium Stadium in 2005. Juan Mata started Chelsea's victory over Liverpool at Wembley in 2012.

"The third, less obvious, name is Angelo Henrqiuez. The Chilean is presently on loan at Dinamo Zagreb. He was also on loan at Wigan, when he was named on the bench for the Latics' shock 1-0 win over Manchester City in 2013."

BBC Radio 5 live

Tonight's 5 live sport began at 19:00 GMT as Mark Chapman and guests digest the fall-out from transfer deadline day, Harry Redknapp's resignation and more.

Then, from 19:45 GMT we have full commentary from Old Trafford where John Murray is joined behind the mic by former Cambridge striker Steve Claridge.

Reports on social media suggest some Cambridge United fans are delayed on the M6, external and are far from certain to make it to Old Trafford in time for kick-off.

In fact, the Cambridge team bus got caught in traffic, external earlier this afternoon, before it even managed to get out the the city. The reason? This:

Image source, @edwardssport

Fulham

Bad news for Fulham as club captain Scott Parker is not fit enough to play and is not in his side's 18-man squad. Jazz Richards, on loan from Swansea, is cup-tied so Jack Grimmer comes in, with Seko Fofana and Alex Kacaniklic also starting. Lasse Vigen Christensen is among the substitutes.

Fulham XI: Bettinelli, Grimmer, Hutchinson, Bodurov, Stafylidis, Fofana, Tunnicliffe, Kacaniklic, McCormack, Rodallega, Woodrow.