Liverpool captain Virgil van Dijk said the Reds must react immediately to a Europa League humbling by Atalanta if they are to keep alive their hopes of winning the Premier League in Jurgen Klopp's final season.
Klopp's men were beaten at Anfield for the first time in 14 months on Thursday as a 3-0 victory put Atalanta on the brink of the Europa League semi-finals.
Liverpool are second in a tight three-way battle for the Premier League title, behind leaders Arsenal only on goal difference with seven games to go.
They have less than 72 hours to recover before hosting Crystal Palace on Sunday and can ill afford any slip up against the Eagles.
"It hurts, we didn't lose here for a long time," said Van Dijk, AFP reported. "They punished us for being sloppy in possession.
"This will definitely hurt tonight and then from tomorrow we need to switch it back on to get a result."
Gianluca Scamacca scored twice either side of half-time before Mario Pasalic rounded off a famous night for the Italians, who have only ever reached one previous European semi-final.
"It's a collective thing and we all know we have to do much better," added Van Dijk.
"It hurts but it can't put us down. We have to react pretty quickly."
Klopp admitted the performance of a number of his players came as a shock.
The German had made six changes from the side that drew 2-2 at Manchester United on Sunday.
But even the introduction of Mohamed Salah, Dominik Szoboszlai, Andy Robertson, Luis Diaz and Diogo Jota failed to turn things around in the second half.
"We have to show a reaction immediately on Sunday - that is much more important," said Klopp.
"In this moment it has to feel really bad, the boys must go home and sleep bad that's how it is.
"Then when we meet tomorrow we have to prepare for Crystal Palace, see who is ready to play, these kind of things.
"A lot of performances tonight were really 'oops I didn't know he could play like that'."
