Lille captain Jose Fonte was left frustrated with his own performance in defeat to Chelsea.
The former Southampton defender was at fault for both of Chelsea's goals in Lille's Europa League defeat.
Fonte told RMC: "If you play badly you pay for it. We conceded two goals because we made two mistakes. We are a very young team, we must learn from our mistakes, continue to work.
"We have a lot of talent, we had a good game, but in the end we have no points.
"Maybe the team did not learn anything from the Ajax match. We must learn from our mistakes. There is little to add. We have the qualities to fight against this kind of team, but these are small details, we must be killers, it is the high level, we must improve."