Jurgen Klopp admitted the end of Liverpool's 68-game unbeaten run at Anfield was a "massive punch in the face" as the Premier League champions crashed to a shock 1-0 defeat against Burnley on Thursday.
Klopp's side were beaten in a home league game for the first time since Crystal Palace won at Anfield in April 2017.
Ashley Barnes clinched Burnley's first win at Liverpool since 1974 when he converted an 83rd-minute penalty after being fouled by Reds goalkeeper Alisson Becker.
"It's a massive, massive punch in the face," Klopp said. "We had the ball a lot, created some and didn't finish the situations off.
"That keeps the game open and then they get the penalty. Alisson told me he didn't touch him, but I didn't see it back.
"We lost a game which I think it's actually impossible to lose. But we did it."
Spluttering Liverpool have slipped to fourth place after a second defeat in their last three league games and trail leaders Manchester United by six points.