Manchester City defender John Stones is struggling to make Sunday's derby against Manchester United.
Stones was taken off injured 37 minutes into England's 3-3 home draw with Germany at Wembley on Monday.
He's missed just one of second-placed City's Prem matches this season.
But if he does miss out, then United will still come up against formidable central defenders.
Frontrunners to replace Stones would be Nathan Ake, Ruben Dias, Manuel Akanji and Aymeric Laporte.
