Demetrious Johnson undergoes successful shoulder surgery

UFC flyweight champion Demetrious Johnson went under the knife on Wednesday.

Johnson had successful left shoulder surgery, MMAFighting.com confirmed with Johnson following the procedure. It is unclear at this time how long his recovery will take and when he might be able to return to action. “Mighty Mouse” said he’s been experiencing shoulder pain since December.

The 31-year-old Johnson (27-2-1) is coming off another undefeated year. He went 2-0 in 2017 and in doing so became the most successful champion in UFC history. He also pulled off the consensus Submission of the Year for his armbar against Ray Borg in October.

The UFC is hoping to book Johnson vs. bantamweight champion TJ Dillashaw for the flyweight title later this year, however, no deal is close to being finalized for that fight, sources say, and, if the fight is eventually signed, it is not expected to happen before at least April.