(Reuters) - Liverpool defender Alberto Moreno is doubtful for Sunday's Merseyside derby against Everton after sustaining an injury in Wednesday's 7-0 Champions League win over Spartak Moscow, manager Juergen Klopp has said. "We had a little shadow on the night when Alberto Moreno needed to get substituted. He is a tough guy and if he cannot continue the game then you should consider it could be something serious." "We showed tonight that we learned from the mistakes we made in Sevilla (where the side blew a three-goal halftime advantage to draw 3-3)... now we have to show we have learned from the mistakes after Maribor when we faced Tottenham," Klopp added. "We will be ready again on Sunday and if the crowd is ready to help us, it would be nice."