Sunderland boss Ricky Sbragia has urged Anton Ferdinand to stop dawdling and step up his game.
Using older brother Rio as an example, the Black Cats boss said his Ferdinand often lacked the urgency and determination his sibling demonstrates.
The 24-year-old, who figured in the 2-0 defeat to Everton at the weekend, admitted himself that he is prone to "switching off" from time-to-time.
With Sunderland still not safe from the threat of relegation though, Sbragia says now is the time to concentrate as the Black Cats bid to retain their Premier League status.
"The biggest thing is concentration," Sbragia told the Daily Mirror. "He could be more focused and concentrate more.
"Anton does switch off, he admits it sometimes.
"I asked him the other day if he watched the Manchester United game and saw Rio play, and he said he did.
"I said to him - Did you see him get into his positions early, did you see him sprinting to get there?
"Sometimes Anton dawdles into positions, but Rio gets there right away and then has his rest.
"I told him to look at really good centre-backs, see what they do, see how they recover, how they cover people."
Sbragia insists that should Ferdinand tighten up his game he has the potential to become a top-class player.
"Anton has everything you want and when he gets to 25 or 26 will be a top-class defender, but he's still learning."