The Dallas Mavericks' season has been effectively over for a while, but it's officially over for their legendary big man, Dirk Nowitzki. The Mavs announced on Thursday morning that Nowitzki underwent season-ending ankle surgery. Via Mavs.com:

The Dallas Mavericks announced today that forward/center Dirk Nowitzki underwent surgical debridement of his left ankle. The surgery was performed by Dr. Eugene Curry and Dr. Daniel Worrel at the Carrell Clinic in Dallas.

According to a report from ESPN's Tim MacMahon, the surgery is "relatively minor," and will not affect Nowitzki's decision on whether to play next season. 

In fact, the New York Times' Marc Stein added that the surgery is actually expected to increase the chances that Nowitzki indeed returns.

Early last week, Nowitzki told Stein that he planned to return for a 21st season next fall, despite the fact that he'll turn 40 years old in the offseason. 

"As of now, I'm planning to come back," said Nowitzki, who turns 40 on June 19. "I feel great. I've only missed one game all season. I signed a two-year contract because I wanted to play two more years. And here we are."

In 77 games this season, Nowitzki averaged 12 points and 5.7 rebounds, while shooting over 40 percent from 3-point land -- his highest mark from downtown since 2013.