Christensen spent two years on loan at The Bundesliga outfit and was voted Player of the Season in his first year with the club.

Chelsea this week rejected a move from Barcelona to land Christensen, 22, when the transfer window opens next month.

He has found himself out in the cold for much of the season at Stamford Bridge with David Luiz preferred alongside Antonio Rudiger.

It is in stark contrast to last season, when Christensen played 27 league games.