Manchester United interim boss Ryan Giggs admits they were "flat" for defeat to Sunderland.

United lacked tempo, their passing was poor and they could not find a way through a defence that has shipped 57 goals this season.

The feel-good bubble that surrounded Old Trafford following the interim appointment of Giggs and his fellow Class of '92 graduates has now burst.

"I feel flat, the players were a bit flat, and I don't know why," the Welshman said.

"We controlled possession but we just lacked that quality in the final third, and concentration."