Another unconvincing display from Manchester United was compounded by a needless red card for Angel Di Maria on 9 March as the Argentine added to manager Louis van Gaal's woes.

With United trailing 2-1 to Arsenal in the FA Cup quarter-final, Di Maria was booked for diving and moments later grabbed the shirt of referee Michael Oliver, giving the shocked official little choice but to send him off.

It ended United's hopes of hauling themselves back into the tie and marred what had started off as a bright performance by the man signed from Real Madrid for 60 million pounds ($90.65 million).

Van Gaal, who now has virtually no chance of marking his first season with a trophy, had little sympathy for Di Maria.

"He whistles, so I want to see that on video-tape how he has decided and in what way. But I know, of course, and also Angel Di Maria knows, that he doesn't have to touch the referee. So that is not so smart of him," said van Gaal at the post-match news conference.

When Wayne Rooney cancelled out Nacho Monreal's opener for the visitors before half-time with a flying header, United looked as though they might continue their quest for a first FA Cup since winning a joint record 11th in 2004.

But they faded after the break and now only have a desperate battle for a top-four Premier League finish to play for. That it was Danny Welbeck, sold by van Gaal last summer, who poached the winner after a dreadful mistake by Antonio Valencia only rubbed salt into the wound.

"And when you see the second goal, it was nothing. So, you gave it away, but the man who was doing that was the best man of my team. And that's also for him, so disappointing," Van Gaal said.

Players are often reluctant to celebrate goals they score against a former club but Welbeck clearly enjoyed netting Arsenal's winner. His reaction was a mixture of joy, relief and a release of any pent up feeling of injustice at being cast off by United boss Louis van Gaal last summer.

Welbeck began his Arsenal career in style and a hat-trick in a Champions League game against Galatasaray in October looked set to light the blue touchpaper. But the goals have dried up, partly because of injuries, and his winner against United was only his fourth goal for the club since he destroyed the Turkish side.