After striking out the first four batters, he wound up allowing four runs (three earned) on three hits -- two homers and a triple -- before manager Scott Servais and trainer Rick Griffin decided he was throwing too much with his arm to avoid the foot problem and pulled him with one out in the fourth.
Walker said he'd stopped taping the ankle on his previous start -- eight scoreless innings in a dominant outing against the Indians -- but Griffin said he needs to resume wrapping the foot whenever he starts. Walker will likely throw a flat-ground session on Thursday to see how it feels, but both he and Servais indicated he should be in line for his next start.
"I'm not going to really test it too much," said Walker, who is 3-6 with a 3.69 ERA in 13 outings. "It's a little sore still, but I feel good. I should be fine."
Servais said there is some concern, however, and the club will need to make some provisional plans in case Walker can't go.
"Obviously before we run him out there, we've got to be confident he's going to be able to go out there and not just for an inning, but for five or six innings," Servais said. "But we'll know more in a day or two. Everybody will be in the loop. Jerry [Dipoto] is aware and the Minor League people if we have to go get anybody. But my fingers are crossed. I'm hoping he is able to make that start."
Right-hander Cody Martin is on the 40-man roster and was called up last month when the Mariners needed some brief bullpen help. He's been a swingman for the Triple-A Tacoma and is scheduled to start Wednesday night for the Rainiers, which would likely make him unavailable to fill in on Sunday on just three days' rest unless he's pulled back.
Adrian Sampson has been Tacoma's best starter (7-4, 3.25 ERA in 13 games). He's not on the 40-man, but a spot conceivably could be opened by putting Charlie Furbush on the 60-day disabled list. The 24-year-old from Redmond, Wash., started on Monday for Tacoma, so he'd be available on five days' rest on Sunday.
But for now the Mariners are planning on Walker making his normal turn. And he says he's eager to face Red Sox ace David Price in the afternoon series finale at Fenway Park.
"I'm really excited," he said. "Price is probably my favorite pitcher to watch. He's a lefty, but that's where I kind of got my mechanics, watching him. I like the way he goes after hitters and attacks with backdoor sliders, fastballs, especially when he was throwing 98-99, he pitched in a lot. I really liked that. I've watched him a lot. We're good friends, too. He's a real good dude."