All along, David Ortiz figured he'd be ready to resume playing for the Boston Red Sox when the minimum 15-day term of his disabled-list stint expired Aug. 1.

Last weekend, he realized that wouldn't happen.

Ortiz attempted agility drills before Sunday night's game at Yankee Stadium, but he was unable even to walk without a limp, the soreness in his strained right Achilles tendon only intensifying.

On Thursday, he did some light jogging while the Red Sox took batting practice and concluded he's about "50-60 percent" healthy. Nevertheless, Ortiz said he likely won't do power running drills for another few days, and odds are, he won't play this weekend against the Twins.

"It feels better," Ortiz said before the Red Sox's 5-0 loss to Minnesota in Thursday's series opener. "The (trainers) were a little surprised about how I was moving compared to when we tried in New York. Like the doctors and trainers say, I'm not going to be 100 percent when I come back to play. But when we start doing the power drills and once I start feeling better, I think I'll be ready to go."

Ortiz has been sidelined since July 16, when he injured his heel while running around second base on an Adrian Gonzalez homer.

"I can play with a flat wheel," Ortiz said with a smile. "We've got to get better, though. I don't want to have any setbacks. This is something that's not a game. I was playing with soreness before I got into the situation at second base. Once I shut it down and started learning about that injury, I figured that it's an injury that can put you out for a long time if you don't take care of it. I'm trying to get to the point where there's no risks."