Manchester United boss Jose Mourinho has said that his team are missing "mad dogs" who "bite the ball all the time".
United came from two goals behind to draw 2-2 with Southampton in Saturday's Premier League clash at St Mary's.
The Red Devils are now 16 points off the top of the Premier League, and six points off fourth-placed Chelsea ahead of Sunday's fixtures.
Mourinho has suggested that more aggression and work-rate from his midfielders would have helped the team overcome Southampton on Saturday.
"We lost so many balls in midfield, so many balls in our transition to the last third that it was difficult to have that continuity," Mourinho told BT Sport.
"We don't have many - I hope people understand what I mean - we don't have many mad dogs, who bite the ball all the time. Scott [McTominay] and [Nemanja] Matic did a very positive job for two midfield players and Phil Jones leads that group of three in a way we are totally in control.
"What we needed to improve in this game is simplicity in midfield. By losing so many balls in midfield, we broke that dynamic that normally leads to goals."
United are next in action at home to Arsenal on Wednesday night.