The Dallas Mavericks were able to pull of the upset on Monday night by beating the Oklahoma City Thunder 85-84 in OKC, tying the series 1-1 going into Dallas for game 3.

However, the win may have come with a big loss.

According to ESPN’s Tim MacMahon, Mavericks’ head coach Rick Carlisle has said that Mavericks’ star forward Dirk Nowitzki is currently listed as day-to-day after an MRI revealed a bone bruise in his right knee suffered in the first half of Monday’s win. Despite the injury, Dirk was still able to play 38 minutes and score 17 points.

“We hope that this is not something that’s going to cause him to miss any time,” Carlisle said.

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At 38 years old, Nowitzki was able to play in 75 of 82 games this season while averaging a team-high 18.3 points and 6.5 rebounds in just over 31 minutes.

The injury comes at a bad time for the Mavericks, who already have J.J. Barea, David Lee, and Deron Williams all listed as day-to-day with various injuries. They also lost Chandler Parsons for the rest of the season earlier in the year.

The Mavericks will play the Thunder again on Thursday in Dallas.