Chelsea defender David Luiz says he and his teammates need to get mentally stronger.
Chelsea suffered a disappointing 3-0 loss to Roma in the Champions League on Tuesday, their fourth defeat in all competitions this season.
Luiz told the London Evening Standard: "Every week is a big week for Chelsea, when you play for big clubs you need to win all your games.
"And you need to learn when you lose. You must improve to do better. We have a big game against a big team. It'll be a tough game, we need to be ready.
"We need to understand why you are here - you are here because you play for a big club, big players need to have a great mentality. These things happen sometimes, and we must be strong."