Nemanja Matic has issued a rallying call to his Manchester United team-mates, saying they will find out who the leaders in the squad are when they take on Valencia in the Champions League on Tuesday.
United are under increasing pressure following their 3-1 defeat to West Ham on Saturday, which has left them 10th in the Premier League having lost three of their seven matches.
Jose Mourinho is unfazed by reports that his future as United manager is under threat, while his relationship with midfielder Paul Pogba remains under scrutiny after the pair had a public falling out on the training ground.
Speaking on Monday, Mourinho said some players "care more than others" and Matic has urged the leaders in the dressing room to step-up against Valencia.
"The leaders need to be on the pitch," Matic said. "The leaders are not scared to play, so we will see tomorrow who are the leaders.
"Everyone has a responsibility. We have spoken between us and we know the situation is not good and we can do better. Everyone is trying to do more for the team.
"Tomorrow is a great chance to do that against a big team. I expect everyone will give more and be more concentrated.
"Saturday we didn't play but we gave our best in that moment. This game was really bad but we have a responsibility for that.
"I don't believe any player goes to the pitch and doesn't give his best. Something wasn't good.
"For me, I played one of the worst games since I signed for Man Utd. I look in the mirror and see where I can do better."