Read: Manchester United v Swansea City match report
New United boss Louis van Gaal lamented his side's lack of cohesion as the team stumbled to a 2-1 defeat to visitors Swansea.
"We are not reaching our level," van Gaal told MUTV.
"That's the main thing. Because of that, we didn't play as a team. Nevertheless, we had chances to win this game.
"We gave a lot of space away in the second half. We played with more pressing.
"They scored one goal out of two chances in the second half."
Ashley Williams, the Swansea City captain, express his pride at the way his teammates responded to the pressure of playing United away from home on the opening day of the English Premiership.
“We couldn’t have asked for any more from that performance,” said the centre-back.
“I’ve never seen a Swansea team with so many players leading by example.
“I’m proud of these guys. We have a really good unit and we get on very well. There’s a big emphasis on that, and I want to be a good leader for them.
“I will remember this game for the rest of my life.” said the skipper on the club's website.