Four days after being activated from the disabled list, David Ortiz was sent back Monday because of lingering soreness in his strained right Achilles’ tendon, which forced him to miss 35 games.

Ortiz said he expected to undergo a platelet-rich plasma (PRP) injection, which he hoped would give him a “60-70 percent’’ chance of getting back to make a contribution during the final 33 games of the season.