Gus Poyet says Lee Cattermole is vitally important to the Sunderland cause - but acknowledges the tenacious midfielder must learn to control his temperament better.
Cattermole has completed a three-game suspension following his red card and looks set to return to Sunderland's starting line-up for their league visit to Villa Park this weekend.
The 25-year-old has been sent off eight times so far in his career but Poyet says Cattermole's winning mentality is vital to the Sunderland cause.
"I need to make sure Lee knows he is important to the team, and Lee needs to make sure he keeps his cool a little bit better," Poyet said.
"He's an important player. He's a leader, he's strong and he doesn't accept defeat - and sometimes you need those kinds of characters."
Poyet also admitted his side has been boosted by Wes Brown's overturned red card after the club appealed his dismissal in the 2-0 defeat at Stoke last weekend.
"I think it is important for many reasons because we are trying to create some consistency in the team especially at the back, because I think we are getting better," he said.
"When you have a player like Wes in your team it's definitely a little bit easier. We had a couple of interesting days waiting to see if he would be available, and after his clearance it made our preparations a lot easier."