The Red Sox recalled Rivera from Triple-A Worcester and placed him on the 60-day injured list Tuesday due to a lumbar strain.
The left-hander landed on Worcester's 7-day injured list in late August due to the injury, and his transition to the MLB 60-day IL will bring an end to his 2026 season. Rivera made his first four big-league appearances and recorded a 6.30 ERA, 1.40 WHIP and 10:6 K:BB in 10 innings.