LIVERPOOL, April 12 — 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.