Borussia Dortmund defender Mats Hummels has officially departed the club. The veteran star’s contract has expired following the most recent season. Although there was speculation that the two sides may work on a new extension, Hummels now becomes a free agent.

Hummels played 13-and-a-half seasons with the BVB in two separate stints at the club. After initially joining the team on loan from rivals Bayern Munich in 2008, the center-back signed a permanent contract with Dortmund a year later. During his first spell with the club, Hummels was vital in his squad’s two Bundesliga triumphs in back-to-back seasons.

After moving back to Bayern in 2016 for around $37 million, the defender eventually returned to the BVB three years later. In total, Hummels played over 500 total matches with Dortmund, winning four major trophies.

“Borussia Dortmund fans, my time at the Black & Yellows has come to an end after 13 years in total,” Hummels said in a statement on Friday. “It was a huge honor and a joy for me to play for BVB for such a long time, and to be almost ever-present on the journey from 13th place in the table in January 2008 to what Borussia Dortmund represents today.”

“This club and its fans are special – and for me, they’re much more than that. I would also like to thank all the staff at BVB who do outstanding work for this club, plus of course, the countless fantastic coaches and teammates I have worked and played alongside.”

Dortmund manager also left the club on Thursday

News of the defender’s official departure comes just one day after Dortmund manager Edin Terzic also left the club. The coach endured a difficult domestic campaign with the BVB but also guided them to the Champions League final. Real Madrid eventually topped the Germans 2-0 on the night.

Ahead of the massive match, Hummels made disparaging comments regarding his coach. Just days before the Real game, the defender told Bild that he was “furious” and “felt insulted” by Terzic’s Bundesliga tactics. Dortmund’s coach was not a fan of the remarks. As a result, Terzic confronted Hummels in the days leading up to the Champions League final.

Hummels took to social media on Thursday night to post a cryptic message seemingly directed at Terzic’s departure. The defender posted a selfie on his Instagram story along with the caption: “Summarizing today will be a challenge for me.”

Hummels could be joining Christian Pulisic at Milan

With Hummels now free to sign with any club, the center-back will likely have plenty of suitors. There have been previous suggestions that the German could opt to move to Saudi Arabia or Major League Soccer. Nevertheless, a stay in Europe now seems probable.

One particularly interesting possible destination for Hummels is to join AC Milan. Rumors surfaced earlier in the week that the Italian side could be the most likely option for the defender. Milan officials are also apparently willing to offer Hummels a significant contract.

The potential move would keep the veteran in the Champions League, as Milan finished second in the Serie A table last season. Fellow Italian team Roma, however, is also reportedly interested in Hummels as well.