He is listed as day to day, sustaining the injury as a result of a couple of plays in the late innings.
First, there was a triple by Yandy Diaz in the sixth in which Betts made contact with the wall. In the seventh, he tweaked it further chasing down a double by Jose Ramirez.
"I think initially it was going back when I ran into the wall. I kind of hit it there," said Betts. "I was fine and able to play through it. When I jumped on that ball going back, I came down and landed on that same spot. That's when it got pretty tough. It felt pretty tender."
That said, Betts is confident it is nothing serious.
"No, there was no twist or anything. I think it was just impact. It swelled up a little bit and got kind of tight. We'll see how everything goes," said Betts.
It seems doubtful Betts will start Friday, when the Red Sox open a three-game series at Fenway Park against the Orioles. But Betts didn't want to rule anything out.
The Red Sox are already without center fielder Jackie Bradley Jr., who was placed on the disabled list Wednesday with a left thumb sprain.
Newly acquired Rajai Davis, along with Chris Young and Brock Holt, will be counted on to help fill the void in the outfield while Betts and Bradley are out.