OAKLAND -- The Mariners starting lineup had Matt Tuiasosopo's name on it for the first time Thursday, but probably not where you might expect it -- at first base.

"The reason is two-fold," manager Don Wakamatsu said. "No. 1, we talked about getting everyone in during this series to create team unity and Tui needs to play to stay sharp. It also gives us an opportunity to get Sweeney in there."

Sweeney, who batted .500 during Spring Training to earn a spot on the Opening Day roster, and Tuiasosopo, who batted over .300 this spring, were the only position players that had not appeared in a game this season.

The Rangers are scheduled to start one left-hander in the upcoming three-game series, "which gives us another opportunity to juggle the lineup a little bit more," Wakamatsu said. "But the biggest thing was to get everyone in there in this [Oakland] series."

This was Tuiasosopo's first game at first base in his professional career.

Colome replaces Langerhans on roster

OAKLAND -- It didn't take long for the Mariners to make their first roster move of the season.

After just three games, the Mariners on Thursday promoted right-hander Jesus Colome from Triple-A Tacoma. To create a roster spot, outfielder Ryan Langerhans was designated for assignment.

Seattle has 10 days to trade, release or outright Langerhans to the Minor Leagues.

"It comes down to how much we would use Langerhans at this point," manager Don Wakamatsu said. "After these three games, and going into Texas with that hitter-friendly ballpark, it's probably not going to get any easier. We have to protect these guys now and long-term a little.

"We don't want to put stress on the bullpen this early in the season, and Colome brings depth and versatility in the bullpen."

Right-handers Mark Lowe and Brandon League, both used twice in the series, were unavailable for Thursday's series finale. Lowe threw 34 pitches in back-to-back games Tuesday and Wednesday nights while League threw 40 pitches on Wednesday night after throwing 15 in Monday night's season opener.

"When you get guys up to the 30- to 40-pitch count, you have to give them one or two days off," Wakamatsu explained. "That's why we needed to make this move today."

Colome joined the team early Thursday morning and pitched three innings, allowing three hits and two runs in the Mariners' 6-2 loss to Oakland.

"Colome came in and did a phenomenal job," Wakamatsu said. "He gave us the innings we needed and our bullpen is in great shape going into the next series [a three-game set against the Rangers in Arlington beginning Friday night]."

Wakamatsu said he prefers using Lowe, Sean White and David Aardsma no more than one inning at a time to keep them fresh, and the addition of Colome would make it easier to do that.

Colome, 32, has pitched in the big leagues in each of the past nine seasons, compiling a record of 19-26 with a 4.66 ERA over 328 relief appearances with the Nationals.

He also has pitched in the Oakland and Tampa Bay organizations.

The 30-year-old Langerhans appeared in one game with Seattle this season, flying out as a pinch-hitter on Wednesday night. He played in 38 games for the Mariners last season, batting .235 (22-for-101) with six doubles, three home runs and 10 RBIs. He hit a pair of walk-off home runs during the 2009 campaign -- Aug. 7 against Tampa Bay and Aug. 25 against Oakland.

Langerhans received the news around 10 a.m. PT, when he was called into Wakamatsu's office at the Oakland Coliseum.

"Anytime you have 11 pitchers, you know the chances of the bullpen getting stretched are there," Langerhans said. "You never expect that you will be the guy, so it was somewhat of a surprise."

Langerhans was acquired from the Nationals on June 28, 2009 in exchange for Mike Morse. He has appeared in parts of seven Major League seasons, combining to bat .232 with 27 home runs in 512 games.

He accompanied the team to Texas following Thursday's game, met his wife and drove to their home in Austin.

"The waiver period doesn't end until Monday," he said. "I hope to get claimed, but at the same time, I really enjoy it here. This is a good ballclub and good people, and I really wanted to be part of what's going on here."

If unclaimed, he said he probably would report to the Tacoma club.

Moore victim of obscure rule

OAKLAND -- Mariners rookie catcher Adam Moore learned the hard way on Thursday afternoon that he can't use his mask to stop a rolling baseball.

The strange play occurred in the eighth inning when, with a runner on first, Athletics shortstop Cliff Pennington bunted toward third base. Jose Lopez attempted to field the ball with his bare hand, but the ball went off his hand and close to the third-base line.

Moore was moving up the line toward third base, and attempted to scoop the ball up with his mask.

The umpiring crew huddled for several minutes and advanced both runners one base. According to the rule, Pennington was credited with a double.

Tuiasosopo named emergency catcher

OAKLAND -- After Rob Johnson was replaced by a pinch-hitter in the top of the ninth inning on Wednesday night, manager Don Wakamatsu walked up to Matt Tuiasosopo in the dugout and said, "You are a true utility guy now, including catching."

And just like that, Tuiasosopo learned that he is now the emergency catcher behind Johnson and Adam Moore.

"I said, 'All right,'" the rookie said. "I have done some catching in the bullpen, and Wak actually mentioned it to me late in the season last year. When I was in Puerto Rico playing winter ball, I would go down to the bullpen and catch the pitchers."

Rarely does an emergency catcher get used, but Tuiasosopo began getting his mind and body prepared in the bottom of the ninth inning when Moore was felled by a foul ball.

"I knew Adam would be fine, but everyone started looking at me, started laughing and told me to get ready," Tuiasosopo said. "I have never caught in a game, but I have been asking what the signs are."

The only other potential third catcher is Mike Sweeney, who started his career behind the plate.

"Uh, no," Wakamatsu said when asked if it ever crossed his mind to use Sweeney as the third catcher.