Ortiz will fly back to Fort Myers, Fla., on Thursday to continue his exercises there and hopes to play in an extended spring training game there.
Not long after, Ortiz should start an official rehab assignment for Triple-A Pawtucket.
"In talking with David, I think he'd feel comfortable with 25, 30 at-bats, likely to be taking place at Pawtucket," Farrell said. "When that rehab assignment begins remains to be seen."
Ortiz originally injured his Achilles tendon on July 20. Ortiz made a one-game comeback on Aug. 24, but he aggravated the injury and hasn't played since.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. This story was not subject to the approval of Major League Baseball or its clubs.