Former Manchester United captain Roy Keane has defended PSV Eindhoven's Hector Moreno for breaking Luke Shaw's leg by saying the defender produced "a brilliant challenge."

United manager Louis van Gaal thought Moreno should have been sent off for the first-half tackle during PSV's 2-1 Champions League victory on Tuesday.

But while Shaw suffered a double fracture and could be out for six to nine months, Keane, who captained United from 1997 to 2005, insisted Moreno did nothing wrong.

"I thought it was a brilliant challenge," he is quoted by the Daily Mail as telling ITV. "I love the physical side of the game.

"You can always tell by player reactions and none of the United lads at the time -- and players are the best judges because they are nearest the tackle -- reacted over the top thinking it was a bad challenge.

"And when players are travelling that speed, defending like that, injuries are going to happen. I'm surprised there are not more like it. It was more of an accident at the end of it with his trailing foot."

Van Gaal, in his news conference after Tuesday's game, described Moreno's challenge as "a very bad tackle with two legs."

The injury was compounded by the fact that UEFA handed the Mexico international its man of the match award for his performance, with the Daily Telegraph reporting that the move angered the Premier League club.

Hector Moreno's challenge left Luke Shaw with a broken leg. VI Images via Getty Images

When Shaw was substituted, Van Gaal moved Daley Blind, who had started the season alongside Chris Smalling in the centre of defence, to left-back.

The Dutchman did not sign a central defender in the summer and Keane claimed he may need to buy two now.

"You are on about the money United have invested," he added. "I think going forward they will be fine. In midfield they are not too bad but I think they are crying out for a centre-half -- definitely one, possibly two.

"It was a poor result and performance. They gave away bad goals and certainly had chances to get something from the game. Overall, it was a disappointing night for United, with the bad injury. I still think United are all over the place."