"I feel better today than days before," Ortiz said Wednesday. "Hopefully, I will continue feeling better every day. We'll see if I can go back into the fire."
The slugger does not have any pain when he walks but will need to run before he is activated from the 15-day disabled list.
"If I continue feeling better and I'm pain-free walking, I'll start doing some running things," Ortiz said.
Wednesday marked the first day the designated hitter was eligible to return from the DL, but he is still a few days away. There was heavy rain at Fenway Park before Wednesday's game against the Tigers, which prevented Ortiz from doing agility drills on the field. Instead, he worked out inside.
"I haven't done anything outside yet. I'll do things outside probably in the next two or three days," he said. "The doctor checked me out every day, and he found less tendinitis on my Achilles [today], so that's good."
Ortiz leads the Red Sox with a .316 average and 23 home runs. He's been hitting since Friday and took swings in the batting cage Wednesday.
"[Tuesday's] batting practice was great, but he was still a little hesitant to run or jump or move quickly. He said today when he woke up was the first day he had no pain walking," said Red Sox manager Bobby Valentine. "He's getting closer.