Red Sox's Castillo out indefinitely with strained left oblique

Rusney Castillo downplayed the seriousness of an injury while speaking to reporters Wednesday.

The Boston Red Sox outfielder is out indefinitely with a strained left oblique, manager John Farrell announced.

"He's going to be down for some time," Farrell told ESPN's Gordon Edes. "I don't have a time frame to give you or a projected length, but he's going through some treatment to calm down the strain right now, and he'll do rotational exercises and rehab when he's ready for it."

Castillo said the injury wasn't serious earlier Wednesday and that he was hopeful to play Thursday. His manager and the team's medical stuff obviously don't feel the same way.

The injury opens the door for Mookie Betts and Jackie Bradley Jr. to get some additional playing time in center field. Betts could displace Castillo as the starting center fielder with a strong spring, or bump Shane Victorino from right field. Betts can also play second base, but veteran Dustin Pedroia has a firm grasp on the position.