OAKLAND -- Mariners shortstop Brendan Ryan was scratched from Saturday's lineup about 90 minutes before game time against the A's due to a stiff neck, with Munenori Kawasaki taking his place for his Major League debut.

Ryan, 30, missed the last few weeks of last season and was slowed at the start of Spring Training with a pinched nerve issue, but manager Eric Wedge said he didn't believe this problem is related.

"He just slept wrong," Wedge said. "It's nothing related to what he's been through in the past. With an off-day tomorrow, I don't want to push it. I don't want one day to turn into a week or 3-4 days, so it's my call on that one."

Ryan went 2-for-3 with a double, a walk and two runs scored in Friday's 7-3 victory and was hitting .300 after three games. He was wearing an ice pack on his neck in the clubhouse prior to warmups, and Wedge informed Kawasaki he'd be in the lineup just before the team took the field for batting practice.

Kawasaki, 30, was an eight-time All-Star shortstop in Japan who made the Mariners as a non-roster invitee with an outstanding spring. Though he was regarded primarily as a defensive stalwart when he signed with Seattle, Kawasaki had the top batting average of any player in either Arizona or Florida, batting .455 (20-for-44) with 13 RBIs in 15 Cactus League games.

He hit .619 (12-for-19) over the final five spring games.

"We want to make sure Ryan's OK, that's first and foremost," Wedge said. "But it's a good opportunity for Mune to get in there."

The Mariners face fellow Japanese standout Yu Darvish on Monday in Texas, where the 25-year-old right-hander makes his Major League debut for the Rangers. Kawasaki will be the only Mariners hitter who has faced Darvish outside of two unofficial at-bats by Ichiro Suzuki in World Baseball Classic warmups in 2006 and '09.

But Wedge said that doesn't mean Kawasaki will be in the lineup Monday.

"We'll play it by ear right now," Wedge said. "Brendan Ryan is our starting shortstop, but Mune can play other positions as well. We'll just see how it plays out here the next couple days."

Wedge plotting Montero's debut at catcher

OAKLAND -- Mariners rookie Jesus Montero was at designated hitter for a fourth straight game Saturday against the A's, and manager Eric Wedge said it would likely be somewhere during the four-game series in Texas next week when he makes his debut at catcher.

Montero, 22, became the first rookie in Mariners history to start at DH on Opening Day and the first in the Majors since Ken Harvey for the Royals in 2003.

Seattle's club record for rookie starts at designated hitter is 52 by Juan Bernhardt in 1977, the franchise's first year.

Veteran Miguel Olivo has remained Seattle's starting catcher because Wedge wants to work the highly regarded Montero in slowly behind the plate, while having his right-handed bat in the lineup every day.

"We'll probably [play him behind the plate] at some point this next week," Wedge said. "The off-day Sunday helps us with Miggy, but then we play seven or eight in a row, so we'll get him back there sometime in there."

Montero worked with all the starters during Spring Training, and Wedge said the youngster won't be aligned with any particular pitcher during the season.

"I don't think so right now," Wedge said. "I'm comfortable with him back there with anybody."

Montero caught a bullpen session before Saturday's game as Blake Beavan and Kevin Millwood both got some side work in to keep them fresh for their starts on Tuesday and Wednesday in Texas.

Wedge still establishing bullpen roles

OAKLAND -- With four rookies in his seven-man bullpen, Mariners skipper Eric Wedge is still working out who exactly will fill which relief roles. But obviously some new guys are going to be called on quickly to establish themselves.

For instance, 21-year-old Erasmo Ramirez was warming up in the eighth inning of Friday's game when Tom Wilhelmsen got in some hot water by giving up singles to three of the first four batters he faced.

Wilhelmsen bore down and got out of that jam by striking out Yoenis Cespedes and Kurt Suzuki, but clearly Wedge won't be afraid to go to the strike-throwing youngster from Nicaragua in tough situations.

The other rookies are Rule 5 Draft pick Lucas Luetge, Japanese veteran Hisashi Iwakuma and right-hander Steve Delabar, who pitched six games for Seattle last year.

"I'm not sure exactly what his role will be yet," Wedge said of Ramirez. "It's a little tough here early on because a couple guys haven't been in a big league game and we're still establishing roles with most of our guys down there, with the exception of Wilhelmsen and [Brandon] League.

"Then we've got the off-day Sunday, we're coming off Spring Training II, so we're just trying to navigate this thing and get into our routines."

But Wedge liked what he saw from Ramirez "from Day 1" this spring, as the youngster came to camp along with top prospects Danny Hultzen, James Paxton and Taijuan Walker and became the one who survived the cut.

Wedge doesn't rule out an eventual return to the rotation for Ramirez, who says he came into pro baseball as a reliever in the Venezuelan Summer League in 2008 but quickly was converted to a starter.

"I think he's a guy that can go either way," Wedge said. "I'm looking forward to seeing him out of the bullpen first. In regard to where he ends up, he'll be able to dictate that to us just by what we see. My thought process with him is this is a good way to break him in, in the bullpen. Then we'll see where it goes from there."

Worth noting

• Left fielder Mike Carp, who stayed behind in Arizona to rehabilitate a sprained right shoulder, continues swinging a bat and improving his range of motion as he works toward a potential return by the home opener on Friday in Seattle. Carp will throw on Sunday for the first time since going on the 15-day DL after hurting himself in the season opener in Tokyo on March 28.

Franklin Gutierrez also continues working to rehab his partially torn pectoral muscle. Gutierrez is getting close to a full return as well, but he'll need to start in the Minor Leagues first since he missed almost all of Spring Training.

• Felix Hernandez will turn 26 on Sunday, already having made 207 starts in a Major League career that began at age 19.

• The Mariners 25-man roster to open the season is the second-youngest among American League clubs and fourth among all Major League teams with an average age of 28.33. Only the Royals (27.42), Astros (27.82) and Braves (28.27) are younger.

If you include everyone on the 40-man rosters, the Mariners are third in the Majors at 26.96, behind the Royals (26.83) and Astros (26.87).

• Jason Vargas became just the fifth Major League pitcher since 1980 to start back-to-back games for his team against the same opponent and first since the Rangers' Aaron Myette vs. the Angels on Sept. 3-4, 2002.

Gil Meche was the last Mariners pitcher to start consecutive games against any opponent when he pitched back to back around the All-Star Game in 2006. Freddy Garcia is the only previous Mariners arm to pitch in that situation against the same team, having faced the Angels on Sept. 10 and 18, 2001, due to the 9/11 cancellations.