The Red Sox are expected to select Rivera's contract from Triple-A Worcester on Wednesday, Chris Cotillo of MassLive.com reports.
Rivera reported to Triple-A Worcester on Tuesday, but he's now set to join the big-league roster before ever making an appearance with the WooSox. The 22-year-old has allowed just one earned run while compiling a 16:3 K:BB over 10 innings (two starts) at Double-A Portland. The Red Sox have an opening in their rotation, but they could limit Rivera to long-relief duty while he's in the majors.