The Reds won the friendly 3-2 but the shot-stopper once again stole the headlines with his blunder.
Oliver Norburn sweetly struck a free-kick at the Reds goal, right down Karius's throat. But Karius, who made two major blunders in the Champions League final against Real Madrid, failed to catch the ball as it bounced back out in front of him.
Tranmere's Jonny Smith then appeared first on the scene to score from the rebound on his first senior team appearance for the club.
As the hosts celebrated their goal, Ben Tollitt appeared to turn round to Karius and yell "you're f****** s***", reports the Mirror.