Oviedo (elbow) will begin a rehab assignment at Triple-A Worcester on Thursday, Chris Cotillo of MassLive.com reports.
Oviedo has been out since early April due to a flexor strain in his right elbow, but after building up gradually over the course of the season, he's now ready to test his elbow in a game setting. The 28-year-old will likely require multiple rehab outings before rejoining Boston's bullpen, but the door is open for him to return before the end of the regular season.