Manchester United manager Louis van Gaal put his side's 2-1 defeat by FC Midtjylland down to Murphy's law.

Memphis Depay put the visitors ahead in the first leg of their Europa League last-32 tie, but Pione Sisto and Paul Onuachu gave the hosts victory.

Van Gaal, already without 13 players, lost David de Gea during the warm-up and used an adage that means anything that can go wrong will go wrong.

"It is the law of Murphy I think," the Dutchman told BT Sport.

"A lot of things are happening in the heads of the players and in the first 10 or 15 minutes we were not so good."

Van Gaal felt his side improved as the first half went on and could have scored more goals.

But he added: "In the second half we didn't win any duels, any second balls. You cannot afford a second goal, but we could have scored also.

"Jesse Lingard had two remarkable chances."

'Nothing to do with attitude'

At the end of the game, United fans in the MCH Arena made it clear they were not impressed with their side's display.

Van Gaal accepted the second-half performance was not good enough, but defended the attitude of his players.

"The fans can criticise," he said. "They can do it because when you see the second half, maybe they are right. We have to improve and then the fans shall support us again.

"All the players want to perform in an excellent way.

"It is not a case of attitude. We were not winning the second balls - that is my analysis."

De Gea set for scan

De Gea hobbled out of the warm-up with a knee problem, but Sergio Romero proved an able deputy - making several fine saves.

Van Gaal was unable to say how long his first-choice goalkeeper would be out for.

He said: "We have to wait for a scan, then maybe we can say more but it was a big surprise."