Isaiah Thomas, Matthew Dellavedova

Boston Celtics' Isaiah Thomas (4) passes after tangling with Cleveland Cavaliers' Matthew Dellavedova, from Australia, in the third quarter of a first round NBA playoff basketball game Sunday, April 19, 2015, in Cleveland. Thomas scored 22 points off the bench to lead Boxton in a 113-100 loss to Cleveland.

(AP Photo/Tony Dejak)

LAS VEGAS -- Isaiah Thomas underwent surgery on his shooting wrist this offseason, a league source confirmed to MassLive.com on Saturday night.

In a surprise, Thomas tweeted Saturday that he has been rehabbing from the injury for the past month. Until he publicized the news, the surgery had gone unreported. The league source called the issue "no big deal," but declined to provide further information.

The Boston Globe's Adam Himmelsbach reached Thomas on the phone:

Isaiah Thomas tells the Globe he underwent wrist surgery to remove a cyst caused by an earlier procedure. He hopes to be 100% in 2-4 weeks. — Adam Himmelsbach (@AdamHimmelsbach) July 12, 2015

Thomas told the Globe doctors also "cleaned out a few things" in his wrist. “Working on my right hand while I'm down lol," he said in a text — Adam Himmelsbach (@AdamHimmelsbach) July 12, 2015

Thomas watched the Celtics summer league team in Utah earlier this week without a brace or any other hint of the injury. During a chat with reporters, he said he has liked Boston's offseason moves so far, but believes Danny Ainge might not be done.