Donny van de Beek suggested Manchester United's players lost confidence after conceding a freak opening goal to Demba Ba during their defeat by Istanbul Basaksehir.
United were caught out by a long ball, onto which Ba latched before slotting beyond Dean Henderson to put the Turkish side 1-0 up. The United defence was then caught out again in the first half, as Edin Visca fired in a second Basaksehir goal to leave United shellshocked.
And although Anthony Martial got a goal back before half-time, United could not make headway in the second half and went down 2-1, their first European defeat of the season.
Speaking to BT Sport after the game, Van de Beek could not explain the opening goal but said it affected United's confidence and they could not recover.
"I need to say I'm really disappointed," said the Dutchman. "We started okay, the first 10 minutes, and then we give a goal away, I don't know how. And after that we lost confidence and we can play much better."
Van de Beek refused to single out the defenders but said United's forwards should have done more to fashion more chances following Martial's goal.
"We are a team and everyone has a responsibility," he added. "We can play much better. I had a feeling [when Martial scored] that there was lots of space to create something, but today we created not many chances.
“For them it’s a really nice win and for us, it’s really disappointing. We need to improve a lot.
“We are Man United and we need to improve. The Arsenal game is the same, we have to step up for the game against Everton.”
