Petsos has Bundesliga experience
The 24-year-old will be returning to the country of his birth this summer, and will join his fourth German club.
Born in Düsseldorf, Petsos began his career with Bayer Leverkusen but made just on substitute appearance for the first-team before heading to 1. FC Kaiserslautern.
Impressive in Austria
Petsos has found home and success in Austria, becoming an important part of their midfield across the past three campaigns.
In that time he has featured 91 times, chipping in with seven goals and four assists. He is also a Greek international.
His versatility has also been called upon during his time in the capital. Petsos has featured from centre-back through to attacking midfield, as well as on the right wing.
Eichin gets his man
Eichin, the Bremen sporting director, was pleased to have brought in the talented defensive midfielder. "We have been watching Thanos for a long time and now had the opportunity to sign him," he said.
Eichin - who was talking to the club website - added, "He comes with experience, but can still develop as a player." He also believes Petsos "fits perfectly to our [Bremen's] style" and that they are "very happy" that Bremen managed to convince him to join.
Werder had reportedly signed FC St. Pauli striker Lennart Thy this weekend on a deal that would take effect in the summer.
However, there has been no official line in respond to the story that came from GOAL.com.
It is a move that would make sense, given Thy's form and the lack of options up front for Viktor Skripnik has up front.
Claudio Pizarro and Anthony Ujah don't have the natural pace and ability to run for the entire 90 minutes, so Thy might be the alternative he is looking for.