Dallas Mavericks forward Dirk Nowitzki underwent season ending ankle surgery on Thursday according to a report by Tim MacMahon of ESPN.

The surgery is considered minor and is not expected to impact his decision to either retire or return for a 21st NBA season.

The 39-year-old appeared in 77 games this season for the Mavericks and averaged 12.0 points and 5.7 rebounds, his lowest totals since becoming a full-time player in the league.

Nowitzki is a 13-time All-Star and captured the NBA championship in 2010-11 with the Mavericks.