Cobb pitched well for Triple-A Durham on Saturday night. He allowed one run on five hits in four innings, striking out one and walking none. Ronnier Mustelier, the Gwinnett Braves left fielder, homered off Cobb with two outs in the second inning.
"Talked to [Cobb] today," Rays manager Kevin Cash said Sunday. "He's going to meet us tonight in Boston. I think he felt good by his results. It was good to go out there and kind of command the baseball the way he knows that he's able to do.
"...I think throughout the rehab process, there's been an inning or two here or there -- we know it's normal, but it's tough for the pitcher whose coming back to understand it's a process that takes a little time."
Cobb will be activated Monday, and Cash allowed that the righty will likely start on Friday or Saturday against the Blue Jays at Tropicana Field.
"All good, can't wait to get back with the guys," said Cobb responding to a text Saturday night.
Cash told reporters on Sunday that the Rays have not yet decided if they will go to a six-man rotation in September.
Cobb has not pitched in a Major League game since the 2014 season, when he went 10-9 with a 2.87 ERA. He had Tommy John surgery early in the 2015 season.
Cobb is 35-23 with a 3.21 ERA in 81 career starts, all with the Rays.