(CBS) Major League Baseball is looking into a domestic violence accusation against Cubs shortstop Addison Russell, sources confirmed.

The league is looking into the matter but stopped short of calling it a formal investigation, sources told CBS 2’s Sandra Torres and 670 The Score’s Bruce Levine.

Russell’s wife, Melisa, published an Instagram post Wednesday evening while the Cubs-Marlins game was being played that said the 23-year-old Russell had cheated on her and that indicated the two were breaking up. They were married in 2016. The post has since been deleted.

In a comment that came after the original post, an individual who identified herself as Melisa’s friend told another Instagram user that Russell had hit his wife before.

Later Thursday afternoon, Russell denied the allegation, calling it “false and hurtful.”

Cubs president Theo Epstein called it a “serious allegation” and emphasized that patience is needed for more facts to come out.

Under MLB policy, domestic violence penalties are at the discretion of the commissioner’s office. Legal action doesn’t need to be taken for MLB to punish a player.

Russell didn’t play in Wednesday’s loss. He’s been a part-time player of late, also not starting last Saturday or Monday either amid prolonged struggles.

He’s hitting .209 with a .626 OPS this season.