© 2014 MLB Advanced Media, L.P. All rights reserved.

5/23/2014 11:19 P.M. ET

Saunders resting night after game-winning hit

SEATTLE -- Mariners manager Lloyd McClendon was still impressed Friday with the way Michael Saunders beat out an infield single in the seventh inning of Thursday's 3-1 win over the Astros.

With two outs, the bases loaded and the game tied at 1, Saunders took a 3-2 pitch and hit a high chopper to Astros first baseman Jesus Guzman. Seeing that he and covering pitcher Tony Sipp were nearing first base, Saunders shortened his stride at the last moment and quickly slipped his foot onto the edge of the bag.

The replay review showed that he beat Sipp by a nanosecond. Two runs scored on the play because Stefen Romero was running on the pitch.

"It was amazing what he did. I've never seen that before," McClendon said. "To have the ability to be running full speed -- heck I wasn't athletic enough to do that. I would have probably tripped and broken my neck. That was really good. It really was. It was pretty outstanding."

Saunders, who also finished 2-for-4 with two RBIs to lift his average to .271, wasn't in the lineup for Friday night's tilt against the Astros. Instead, right-handed-hitter Cole Gillespie received a rare start with Houston left-hander Rudy Owens making his Major League debut.

"That's probably more me," McClendon said. "[Saunders] had the banged-up knee and he's been going at it pretty hard. We're facing two lefties in a row, so I thought I'd give him a day."

Walker feels strong after successful session

SEATTLE -- Passing another hurdle in his rehabilitation program, Mariners pitcher Taijuan Walker (right shoulder impingement) threw about 55 pitches in a three-inning simulated game at Safeco Field on Friday.

The 21-year-old right-hander, ranked by MLB.com as the top prospect in the organization and the No. 5 prospect in baseball, touched 94 mph with his fastball and worked in his off-speed pitches while facing teammates Brad Miller, Nick Franklin and Cole Gillespie.

Afterward, Walker said his shoulder felt good and that he's ready to embark on his second rehab assignment of the season.

"I didn't get tired at the end," he said. "I felt like I was strong. I could have gone another inning or so ... everything was game-mode. I wasn't trying to hold back or anything. I was just going right after them."

The Mariners haven't given official word on when or where Walker will be sent in their Minor League system. They also haven't specified how long his rehab stint will last. Walker went 1-0 with a 3.60 ERA last year in three starts during a late-season callup, but he hasn't pitched in the Major Leagues in 2014 while dealing with the shoulder problems.

In late February, the club shut him down for a week when it discovered inflammation in the bursa sac of his right shoulder. He rehabbed during Spring Training and made his season debut in early April with Class A High Desert, allowing four hits and two runs, one earned, in 4 1/3 innings. Then, he was promoted to Double-A Jackson, where he struck out 10 in five shutout innings, giving up three hits in his only appearance with the Generals.

By mid-April, Walker was arguably one step from rejoining the rotation, but he was scratched a few hours before his rehab start with Triple-A Tacoma after complaining of shoulder stiffness. Afterward, he was diagnosed with the impingement.

"I felt like I was right there ready to go, and then I was going to head back up here," he said. "But I just stayed positive. I was able to get ready, get out there and get my work done without being down about it."

Walker said he's altered his mechanics so that it sometimes feels like he's "walking up to the plate" when he finishes his delivery. Following through on his pitches, he said, can relieve the pressure on his shoulder.

"I definitely feel like after I pitch a game it won't be as sore as it usually would because I'm using my legs and finishing, so I'm taking all that stress off my arm," he said.

Romero earns second straight start at DH

SEATTLE -- Rookie Stefen Romero was in the lineup at designated hitter again Friday, though manager Lloyd McClendon moved him up to the second spot in the order a night after he went 2-for-3 with a walk and a run scored while DHing and hitting seventh.

Since regular DH Corey Hart was placed on the 15-day disabled list with a hamstring strain, the Mariners have used Romero, Nick Franklin and Robinson Cano in a DH-by-committee approach.

"Somebody's got to DH," McClendon said. "It's just that simple. [Romero] got two hits. He probably earned the right to get back in there."

Worth noting

• Entering Friday's action, Dominic Leone ranked second among American League rookie relievers with 23 strikeouts after picking up his first career win Thursday with 1 2/3 scoreless innings.

• The Mariners have had 28 games this season decided by two runs or fewer, most in the AL. They're 14-14 in those contests.

Adam Lewis is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.