Louis van Gaal admits West Ham striker Andy Carroll could run riot in tomorrow's FA Cup quarter-final replay if his Manchester United defence does not improve.

Carroll scored a brilliant hat-trick against Arsenal on Saturday, terrorising the Gunners' back-line in what was only the striker's first league start since January.

The 6ft 3in forward's performance has pushed him back into the reckoning for England's Euro 2016 squad this summer and he will be confident of capitalising again versus a United side vulnerable after a 3-0 drubbing at Tottenham.

The defeat saw the Red Devils concede three times in six minutes at White Hart Lane and Van Gaal is well aware a similar display could spell the end of his team's FA Cup hopes.

"I've seen the Andy Carroll show (against Arsenal) and I think our problem against Tottenham was also the miscommunication of our central defenders," Van Gaal said.

"I hope that we improve our communication because it is very important this game for us.

"Carroll has special qualities. We have seen that in the match that he played on Saturday. It was also against Arsenal and they have great central defenders but still he could do that.

"So we have to cope with Andy Carroll and not only Andy Carroll, the other players.

"They have a certain player called Dimitri Payet for example, he can also play, and (Manuel) Lanzini can also score goals."

Sunday's loss means United trail Manchester City by four points in the race for the Champions League while their hopes of silverware now rest solely on the FA Cup.

West Ham, however, have little reason to be fearful.

They held United to a 1-1 draw in the first game at Old Trafford last month, have not lost at Upton Park since August and, as Van Gaal was keen to point out, will enjoy the benefit of an extra day's rest.

"It is our last chance of a title so it is very important for the players, the club, the manager and the fans," Van Gaal said.

"And still we have one day less than West Ham United. That's also important. We have proved against Arsenal and Manchester City, in spite of less days to recover, we could beat them.

"So I hope we can recover very good, also mentally because the defeat to Tottenham was a blow of course. Everybody knows this is the last chance."