The Mariners aren't ready to make any pronouncement on whether Millwood will be ready for his next scheduled start, which would be Monday against the Orioles, but he sounded optimistic after testing out the leg and said trainers think it might just be scar tissue breaking up from his prior injury.
"It felt fine," said Millwood, 37. "I didn't feel it at all, which is definitely a positive, but it's also a little confusing. Hopefully it's just some scar tissue and I can get back out there soon."
Millwood originally strained the muscle on June 8, six innings into a no-hitter against the Dodgers. He was removed from that game and his next start was pushed back three days, but he'd been fine until feeling pain in the third inning of Wednesday's start against Oakland.
"I threw three more pitches after that, but it hampered what I was trying to do," said Millwood, who was lifted after 2 2/3 innings. "At the same time, it wasn't as bad as last time."
Manager Eric Wedge said the team is waiting for further doctor reports, but he was encouraged that the injury doesn't seem to be a lingering situation.
Millwood (3-6, 4.00 ERA) said it was frustrating to come out of a game when he felt he was throwing well, having given up just a leadoff home run in what turned out to be a 2-1 loss on a day Seattle allowed just two hits.
The veteran remains hopeful that he won't miss any time after his throwing session went so well Thursday.
"The fact I was able to throw using my legs that much was definitely a positive," he said. "Last time my arm worked fine, but I wasn't able to get off my back leg very well. Today that was fine."