Bonser, who didn't pitch in the Majors last year following surgery on his right rotator cuff and labrum, tweaked his groin in his start against the Rays on March 22. Bonser pitched in a simulated game on Friday, and he will likely pitch in a Minor League game on Saturday.
"There's still, I think, a pretty good chance he'll pitch on Saturday," manager Terry Francona said. "We'll see how that goes. He's been through a lot. We really like what we see. We don't want to hurt him. [This will] give him a chance to be the pitcher he can be. I think by shortcutting it, I think we feel like we have a chance to mess up. We talked to him and I think he understands. This is a chance to be very cautious with him, also make sure he gets healthy and also give him a chance to get stretched out."
As for Lowrie, he last played for Boston on March 11. Concerned with how much fatigue he had been feeling, Lowrie was examined shortly thereafter, and diagnosed with mono. The switch-hitter was hoping to spend the spring proving to the Red Sox that he was over the left wrist woes that have hindered him for most of his first two seasons. Even if Lowrie had stayed healthy, he might have been hard-pressed to make the Opening Day roster. The club is expected to go with a bench of Mike Lowell, Bill Hall, Jason Varitek and Jeremy Hermida.
"Jed is going to stay down here," Francona said. "We'll get a plan worked out, but I think everyone thought that keeping him on the ground and keeping him in the same place, there's no reason to put him on a plane. He's got his surroundings here and he'll just do what he's going to do."
With the two roster moves, the Red Sox have 33 players left in Major League camp. Daisuke Matsuzaka will go on the disabled list before Opening Day, so Boston has seven more cuts to make before Sunday's Opening Night game against the Yankees.