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04/28/2013 4:22 PM ET

Hultzen expected to miss at least a month

SEATTLE -- Danny Hultzen was at Safeco Field on Sunday, but this wasn't the glorious call-up of one of the game's premier left-handed pitching prospects.

"I don't want to be here for this reason," Hultzen said as he checked in for rehab work after being diagnosed with a rotator cuff strain and tendinitis in his left shoulder after being scratched from his Thursday start with Triple-A Tacoma.

"I'm doing my rehab here, just to get work done with the trainers," Hultzen said. "Then I'll go be a cheerleader for the Rainiers. That's the plan for now."

Hultzen has been told he'll likely need two weeks with no throwing, followed by at least two weeks of rehab, before any decisions will be made on his potential return.

"This is obviously something you don't want to have happen, but I'm going to just stay positive and get through it," Hultzen said. "It'd been bothering me a little bit, just the normal pitcher's tired arm or whatever. Nothing I worried about. But it got to a point where Dwight [Bernard], the pitching coach, asked me if my arm hurt because he could see something. So that's when we shut it down before the game."

Mariners manager Eric Wedge said it was wise of the 23-year-old to acknowledge the difficulty before it got worse.

"It's real important and good for him, being honest and smart about it," Wedge said. "If you feel something that's not right, you've got to be careful. Just total body awareness is such a key thing for these guys. You want them to be tough, but you want them to be aware. If something doesn't feel right, then something probably isn't right and let's at least get it checked out. If it is something, maybe we can preempt something."

M. Saunders expected to return Monday

SEATTLE -- Michael Saunders went 2-for-5 with a double and triple in his second rehab start for Triple-A Tacoma on Saturday and is expected to rejoin the Mariners on Monday, barring any setbacks, after he plays center field for the Rainiers on Sunday in Las Vegas.

Saunders is eligible to come off the 15-day disabled list as soon as he's ready, but the Mariners wanted him to get at least three rehab starts under his belt before he returns. He played designated hitter his first two games and manager Eric Wedge wants to see one start in center field before he takes over as Seattle's starter at that position.

"He texted me last night saying, 'I'm ready' with a slammer on it," Wedge said prior to Sunday's series finale with the Angels. "So he's champing at the bit. I told him to play today and then call me. If all goes well today, I'd say we're looking good for tomorrow."

In his first two games at DH, Saunders went 2-for-8 (.250) with two RBIs, one walk and one strikeout. Saunders had a leadoff triple and scored in the first inning on Saturday, then added an RBI double in the ninth in Tacoma's 8-2 victory at Las Vegas.

Saunders went on the disabled list on April 11 after spraining his right shoulder slamming into the right-field fence at Safeco Field. He was hitting .286 in nine games when he got hurt.

Peguero shows off his speed for Mariners

SEATTLE -- Mariners outfielder Carlos Peguero is 6-foot-5, 260 pounds of power. That was on full display when he launched a 451-foot home run off the center-field batter's eye at Safeco Field in his first at-bat after being called up from Triple-A Tacoma on Thursday.

But the big man can run pretty well also, as he showed by stealing a base during Saturday's 3-2 win over the Angels.

Stolen bases have been a rarity for a Mariners squad that is heavy on power hitters, but shy on speed, particularly after injuries to Michael Saunders and Franklin Gutierrez. Of the current active Mariners, only Brendan Ryan (two) and now Peguero have stolen a bag this season. Saunders and Gutierrez had four between them before both went on the disabled list.

"I take pride in running," said Peguero. "It's part of my game. I don't run that fast, but I can use my legs pretty good to get a good jump. If you can steal a base, why not?"

Peguero was 2-for-2 in stolen base attempts for Tacoma before getting called up and has now stolen 36 bags over nine seasons in the Minors. He's been caught stealing 29 times, but is 12-for-14 over the past three years in Tacoma.

Worth noting

• With Saturday's 3-2 victory over the Angels, Felix Hernandez now has 65 career starts in which he's allowed two or fewer runs in at least eight innings, the most in the Majors since he debuted in 2005.

• Going into Sunday's action, Kyle Seager's 69 extra-base hits since the start of last season are the third most among AL third basemen, trailing only Miguel Cabrera (92) and Adrian Beltre (80). Seager is tied for first in doubles with 45, third in hits with 182 and tied for fourth in home runs with 23.

• Jeremy Bonderman picked up his first win of the season on Saturday for Triple-A Tacoma, allowing two runs on five hits in six innings in the Rainiers' 8-2 victory at Las Vegas. Bonderman walked one and struck out four and is now 1-2 with a 4.61 ERA in five starts.

Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.