Derby County have given Shaun Barker permission to play in two trial matches for Sheffield United's Under-21s as he steps up his rehabilitation from injury.
The 32-year-old hasn't played a competitive game for almost three years but recently made his return for the Rams' Under-21s last month.
On their website this morning, the Championship league leaders said: "Derby are set to utilise the ability to field three overage outfield players in the coming weeks for players either on the fringes of the first-team squad or returning from injury, so the opportunity for Barker would be limited with the Rams.
"In the event that the games go well at Sheffield United, he is likely to have the opportunity to feature in trial matches at other clubs in the coming months to progress his rehabilitation."
A serious knee injury has kept Barker on the sidelines since his last competitive appearance in the East Midlands derby against Nottingham Forest on March 13, 2012.