Olly, 29, has spend today (6 August) at the team's grounds in Germany and was delighted when the players agreed to pose for pictures with him.
The pop star even had his very own personalised football shirt signed but, sharing a picture of it on Twitter, pretended he had been signed!
Alongside a collage of snaps, Olly jested: "The NEW SIGNINGS!!! Delighted to be joining such a big club this late on in my career!! ;)"
Jokes aside, Olly wouldn't be the first former X Factor contestant to land a spot on a football team.
Last week, we revealed how One Direction's Louis Tomlinson has signed for Doncaster Rovers!
Olly is also a dab hand on the pitch. The 'Troublemaker' star recently thrashed Radio 1's Nick Grimshaw 11-1 in a friendly game.
Watch Olly's video for 'Troublemaker' below!