Walker threw 45 pitches in a simulated game on Wednesday in Pittsburgh, and he will face Albuquerque in a 7:05 p.m. PT game Monday at Cheney Stadium.
"Hopefully he'll get five innings, depending on where the pitch count is and if he has an extended inning somewhere in the middle there," manager Scott Servais said. "But that's what we're hopeful for, and then [we'll] reevaluate coming out of that as to whether he can make the next turn or needs another rehab. I'd like to get him back here as soon as we can."
If Walker is ready to rejoin the rotation, he could slide back in as early as next Saturday against the Angels at Safeco Field. Walker is 4-7 with a 3.66 ERA in 16 starts this season.
Outfielder Guillermo Heredia struck out in his Major League debut against former Mariners reliever Mike Montgomery in the eighth inning of Friday's 12-1 loss to the Cubs, but Servais said he hopes to work the 25-year-old Cuban into the mix a little more going forward after he was added to the roster Friday.
"Montgomery pitched him probably better then he pitched anybody else yesterday," Servais said. "He threw him two really good curveballs. It happens. But it's good to get the nerves and the first at-bat out of the way. Now you need to get the first hit out of the way. It's a different look, a younger, athletic [outfielder], but you've got to produce. We'll give him a chance to get in there."
Right-hander Cody Martin played with Heredia in Tacoma, and he came away impressed.
"He's really aggressive, fast, plays a very good center field," Martin said. "He's played a little left and right as well. He's fun to watch. He definitely gets the game going. When he was leading off for us or hitting in the two-hole, he'd get on base and make things happen early, and that puts a lot of pressure on the defense. He's an exciting player."
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.