Toronto Blue Jays pitcher Roberto Osuna was arrested for assaulting a woman Tuesday morning ... law enforcement sources tell TMZ Sports.
Our sources say cops got an emergency call during the alleged attack and raced to the scene.
Once they got there, Osuna was arrested for assault -- we're told the alleged victim is in a relationship with the MLB star.
Osuna has since been released from custody -- he's due back in court on June 18.
The 23-year-old was an All-Star in 2017 and was a prodigy as a child.
He signed with the Blue Jays when he was only 16 years old and became the youngest pitcher in team history to appear in an MLB game.
He recorded his 100th save on April 10.