Updated

(SportsNetwork.com) - The Los Angeles Angels of Anaheim are closing in on a postseason berth.

Rookie Matt Shoemaker is a big reason why and on Monday he goes after a seventh straight winning decision and tries to help the Angels become the first team to clinch a playoff spot in the opener of a four-game series with the Seattle Mariners at Angel Stadium.

Shoemaker has been rock solid for the Angels this season, going 15-4 with a 3.16 ERA. He bounced back from a shaky effort in Minnesota two starts ago to beat the Texas Rangers on Wednesday, as he held them to a run and seven hits in 6 2/3 innings.

He's gone 7-1 with a 1.73 ERA since the start of August.

"Shoe is one of the big reasons we're even contending," Angels manager Mike Scioscia said. "To do what he did is spectacular for us."

Los Angeles had its 10-game winning streak stopped on Sunday, but still leads the American League West by 10 games over the Oakland Athletics. While the Angels will secure at least a wild card spot on Monday with a win, they still hold a magic number of four to capture their first division title since 2009.

"No one's using the word 'luxury' around here," Angels manager Mike Scioscia said. "We were out there trying to win every game."

Seattle, meanwhile, is fighting for its postseason lives and enters this series a game back of the Kansas City Royals for the second wild card spot. The Mariners didn't help themselves any this weekend by dropping two of three to Oakland and now will play the their next 11 away from home before closing their season with a three-game homestand versus the Angels.

Seattle has won eight of its last 10 on the road and are 42-28 as the visitors this season.

'We haven't been good. The good part is we are going on the road where we have been real good," Seattle manager Lloyd McClendon said. "You want to talk about improbable, that's about as improbable as you get."

Getting the call for Seattle on Monday will be righty Hisashi Iwakuma, who lost for the first time in six decisions on Wednesday. Iwakuma lost to Houston in that one, as he allowed four runs and six hits in 4 1/3 innings to fall to 14-7 to go along with a 3.11 ERA.

"Everything was up in the zone," Iwakuma said through interpreter Antony Suzuki. "I couldn't command pitches down in the zone. It cost me the game.

"I couldn't get strike one, which kind of hurt me, too. If you have to throw a strike, they kind of wait for that fastball and that splitter."

Iwakuma is 5-0 in eight games (7 starts) versus the Angels with a 1.64 ERA.

Seattle is 7-5 against the Angels this season.