Manchester United picked up a 4-2 derby win against Manchester City at Old Trafford today - but key midfielder Michael Carrick was forced from the pitch with what seemed to be a serious injury in the dying minutes of the game.
The Red Devils claimed a key win thanks to first-half goals from Ashley Young and Marouane Fellaini, before Juan Mata and Chris Smalling sealed the deal. Sergio Aguero struck a brace for the well-beaten visitors.
However it wasn't all good news as Carrick limped down the tunnel with just a few minutes to play, leaving Manchester United to see out the win with just 10 men. The England international has been key to Manchester United's recent good form which has seen them claim victories in their last six Premier League outings.
The former Tottenham midfielder has endured a difficult season with regards to injury, and he missed four weeks because of a muscle injury at the turn of the year. Van Gaal confirmed after the game that some Manchester United players didn't even know that Carrick had walked off the pitch.
The Dutch boss added: "I think that the second half was much better than the first half, I think we were fantastic until the Carrick injury". He said that that Carrick had suffered a 'stiff calf' and would have to 'wait and see' how long he'd be out for.
Sky Sports pundit Graeme Souness was in no doubt about how important Carrick was to Manchester United's victory today, picking him out as the man of the match.
He said after the full-time whistle: "I enjoyed Carrick's performance today. He makes it look so easy. He kept the ball moving all the time. I thought he was fabulous."
Michael Carrick has earned a lot of praise for his part in Manchester United's revival in recent weeks and rightly so - but this could be a serious problem for the Red Devils.
The midfielder has a chequered history when it comes to injury and Van Gaal will want to treat him with kids gloves - although Manchester United already look assured of a top four finish so any damage done down to his absence should be minimal.