The Red Sox remain unsure whether rookie Marcelo Mayer will play again this season after suffering a wrist injury in late July.

Stephenson had made his return from Tommy John surgery in late May but his return was short lived as he was placed on the 15-day injured list with right biceps inflammation and a stretched nerve.

The Red Sox right-hander threw his first up-and-down bullpen session on Friday, a notable step forward after a series of successful one-inning bullpens earlier in the week. He will now face live ...