German midfielder Marco Reich is training with Palace with a view to earning a permanent deal.
The 27-year-old played for Derby in the Championship last season but, following the Rams failed play-off challenge, left to return to Germany.
During the summer, Reich turned down a possible move to Red Star Belgrade and also saw a potential transfer to Kaiserslautern fall through.
The goalscoring left-winger is now being put through his paces by the Palace backroom staff, and is hopeful of his chances of winning a contract.
"Could I play in England again? Possibly, probably," said Reich.
"I am training with Crystal Palace and we'll see what happens. It is a club I would be interested in because I feel they will be challenging for promotion.
"They certainly look to have goals in the team with Andy Johnson, Jon Macken and Clinton Morrison."
As a free-agent, Reich could sign for Palace even though the transfer window is closed until January.