Sale Sharks boss Bryan Redpath slammed his side's performance in their 29-19 Premiership defeat to London Welsh on Friday.
Redpath was seething after watching his side slump to their fourth straight defeat.
"There weren't any plus marks really as most of our game wasn't up to speed," he said.
"You can't hide behind that performance because, as a group, it wasn't good enough.
"I don't want to take any credit away from London Welsh. They came up here, played a simple game, got in front and stuck at it.
"We have to take that responsibility when the fans booed us off the pitch and that is something we obviously never want to happen again.
"I apologise to every Sale supporter. They pay good money to watch and I will be doing my utmost to rectify that."
London Welsh coach Lyn Jones, whose team claimed their second win in five days, admitted that he was taken aback with their fine form.
"Compared to the first two weeks, are we surprised? Yes, very much so. You've got to be, haven't you? But the more you play like this, the less surprised you get," he said.