Injury-riddled Mariners face Athletics

OAKLAND, Calif. -- The Seattle Mariners are in the thick of the wild-card playoff race in the American League, but they will have to survive three to four weeks without ace Felix Hernandez and two to three weeks without valuable reliever David Phelps.

That double dose of tough pitching news was announced Tuesday by the Mariners, one day after both pitchers underwent testing in Seattle. Hernandez (right shoulder bursitis) has been on the disabled list since Saturday, and Phelps (right elbow impingement) joined him on Tuesday.

"It's tough losing a guy like Felix, and Phelps, a guy in the back end of the bullpen, has been doing a great job," Mariners right-hander Yovani Gallardo said. "It's just one of those things that happens in baseball.

"The guys that are healthy, we got to step it up. We got to step up and fill in those gaps and wait for those guys to get healthy and join the club, and I think when they, do it's going to make us that much better."

Gallardo will try to do his part Wednesday afternoon against the Oakland Athletics when he makes his fourth start since rejoining the rotation after a stint in the bullpen. Gallardo is 1-0 with a 4.02 ERA in his past three starts and 5-7 with a 5.35 ERA overall in 21 games, including 17 starts.

"I feel good," he said. "I got the opportunity to start, to get back in the rotation. I'm just being a little bit more aggressive, more aggressive in the strike zone. Just kind of mixing in, trying to use the curveball a little bit more.

"We've come up with some pretty good game plans going into the starts. Honestly, I think that was the biggest thing, not overthinking and not doing too much and just being aggressive."

Gallardo is 2-5 with a 4.24 ERA in nine career appearances against Oakland, including eight starts. This year, he is 2-0 with a 2.12 ERA in three games, including two starts, vs. Oakland. He beat the A's on April 23 at the Coliseum, allowing one run over 6 1/3 innings, and on May 15 at Safeco Field, giving up three runs over 6 1/3 innings. He blanked the A's over 4 1/3 innings of relief on July 6 in Seattle.

The Mariners opened the two-game series with a 7-6, 10-inning victory Tuesday, getting a tiebreaking, solo home run from Leonys Martin with two outs in the top of the 10th inning off Josh Smith.

First baseman Yonder Alonso made his Mariners debut Tuesday night, two days after being traded by Oakland to Seattle. Alonso went 1-for-5 with an infield single.

The A's called up left-handed-hitting first baseman Matt Olson from Triple-A Nashville for the sixth time this season. Olson, one of the organization's top prospects, will fill the void left by Alonso and start at first base against right-handers in a platoon with Ryon Healy.

Olson entered the Monday game at first base in the top of the eighth inning and singled in the 10th before being replaced by a pinch runner. Olson will be in the starting lineup against Gallardo.

Olson hit .198 with four home runs and nine RBI in 18 games in his first five stints with the A's. He batted .272 with 23 home runs and 60 RBI in 79 games with Nashville. He was the 47th overall pick in the 2012 draft.

Earlier this season, Bob Melvin called Olson Oakland's "first baseman of the future," and the A's manager is eager to see how the rookie performs in his first extended playing time in the big leagues.

"He's having a great year and really deserving to be here," Melvin said. "Obviously with our All-Star there, with Yonder there, it wasn't in the cards for him to be here as a first baseman, and that's his position. When he's been here, he's basically been playing right field for us at times.

"We are excited about seeing what was probably our top prospect a couple years ago and is having another good year this year. Hopefully gets to settle in and show everybody what he can do."

Oakland's starting pitcher Wednesday will be Jharel Cotton (5-8, 5.48 ERA). The right-hander has an 8.31 ERA in two no-decisions since being reinstated from the disabled list on July 30 after recovering from a blister on his right thumb.

"A few of our younger guys have had a little bit of a tough stretch here recently," Melvin said. "That's going to happen over the course of a season, so it's getting back and getting confident and getting a couple games under your belt where you feel confident again. We all know he's talented, so it's just kind of the ebbs and flows in a long baseball season."

Cotton is 1-0 with a 4.35 ERA in two career starts against Seattle. He earned the win in his only start against the Mariners this season on April 22, allowing two runs over six innings.