Manchester United manager David Moyes warned captain Nemanja Vidic that he faces a fight to win back his place in the starting line-up.
Vidic is fit to play in Wednesday's League Cup quarter-final at Stoke City, after missing United's last two matches with a minor injury sustained in the 1-0 Premier League defeat at home to Newcastle United.
However, United kept clean sheets in both those matches -- a 1-0 win over Shakhtar Donetsk in the UEFA Champions League and a 3-0 success at Aston Villa -- despite Vidic's absence.
Jonny Evans and Phil Jones impressed at centre-back against Villa, and with Vidic increasingly plagued by injuries and his regular partner Rio Ferdinand now 35, Moyes says that the old hierarchy is no more.
"Nemanja is just about ready to play now," Moyes told a press conference.
"But we have five centre-halves. We can use Phil Jones, Chris Smalling, Jonny Evans, Rio Ferdinand and him. There is competition for places there and you are going to have to play well to stay in the team."
Moyes will definitely be without striker Robin van Persie (thigh) and midfielder Michael Carrick (Achilles) at Stoke, while there are doubts over Javier Hernandez (head) and Shinji Kagawa (illness).