Toni Leistner has completed his loan move from QPR to Cologne.
Leistner, 29, has been out of favour since soon after Mark Warburton took over as manager in the summer and has returned to his native Germany for the rest of the season.
The deal was agreed on Thursday after Warburton had made it clear to Leistner that he is now behind youngster Conor Masterson in the pecking order of centre-backs.
Rangers made him available for a transfer in July but no move materialised and he subsequently won his place back in the team.
But with Cologne interested, Masterson having broken into the QPR side and Yoann Barbet close to a return from injury, Leistner has moved on.
He has made 65 Championship appearances since being signed on a free transfer after leaving Union Berlin during the summer of 2018.
Leistner has 18 months remaining on his Rangers contract.
Speaking to the club website, Warburton explained: “At this stage of the season Toni wants assurances about first team football and that is something we cannot guarantee any player.
“It is about being honest with the players and if any individual is not satisfied or is unhappy we will not stand in their way.
“The form of young Conor Masterson has entitled him to recent first-team starts and we will always give opportunities to players, regardless of their age.”