Walker said he "got after it" in his pregame session on Thursday, and everything went well.
"It's still a little sore, but I felt good [throwing]," Walker said. "I'm good to go."
Walker is 3-6 with a 3.69 ERA in 13 starts this season with 67 strikeouts and 16 walks in 70 2/3 innings. He struck out 11 with no walks in eight scoreless innings in his previous start against the Indians before allowing four runs (three earned) on three hits -- two homers and a triple -- in 3 1/3 innings against the Rays on Tuesday.
• Center fielder Leonys Martin was rested on Thursday after starting five games in a row following his return from the disabled list with a strained hamstring. Martin went 2-for-4 with a walk in Wednesday's 3-2, 13-inning loss, but manager Scott Servais is being cautious with the 27-year-old's leg.
"He's a little tender," Servais said. "That was the original plan when we brought him back. We didn't want to just run him out there for how many consecutive games. We want to give him a break here or there. He's swinging the bat good and playing good, but he didn't look like he was 100 percent last night."
• Servais credited right-hander Nick Vincent for saving the bullpen from being too overtaxed by Wednesday's 13-inning affair as he took up 2 2/3 of the 7 1/3 frames that five relievers shared.
"He is a gamer, an old-school guy, " Servais said. "Just give me the ball and I'll figure a way to get them out."
• Mariners pitchers had 19 strikeouts in Wednesday's game, only the sixth time in club history the team has recorded 19 or more strikeouts in a game of any length. The franchise record is 21 strikeouts in a game, which has been done three times.
• First-round pick Kyle Lewis, the No. 11 overall selection in last week's MLB Draft, has reported to the Short-A Everett club and will be with the team when it opens its season Friday at the Tri-Cities.
• The Mariners announced that they've officially signed 13 of their 40 Draft picks as of Thursday, including five of the top 10. In addition to Lewis, right-handers Brandon Miller (sixth round) and Matthew Festa (seventh), third baseman Nick Zammarelli (eighth) and third baseman David Greer (10th) are all reporting to Everett.
Also signed and joining the AquaSox are right-hander Michael Koval (11th), lefty Tim Viehoff (12th), outfielders Eric Filia (20th) and Austin Grebeck (21st) and left-hander Elliot Surrey (26th).
Three signees will report to the Arizona Rookie League: outfielder Jansiel Rivera (22nd), right-hander Steven Ridings (29th) and second baseman Joe Venturino.