SEATTLE -- Yonder Alonso finally got his welcome-to-Seattle moment.

Alonso went 3-for-4 with a home run and three RBIs as the Mariners defeated the Baltimore Orioles 7-6 Wednesday afternoon in the finale of a three-game series.

Alonso, an All-Star acquired Aug. 6 from Oakland for minor league outfielder Boog Powell, hit a two-run homer in the fourth inning, his 23rd of the season and his first with the Mariners, to snap a 1-1 tie. Alonso's run-scoring single in the next inning gave Seattle a 5-4 lead.

Leonys Martin also homered and made a key catch in the ninth inning for the Mariners, who won the last two games of the series to get back to the .500 mark at 61-61 and remain in the American League's wild-card race.

"Obviously it was a crazy week, going from one side to the other side," said Alonso, who joined the Mariners while they were playing in Oakland. "These guys made it easy for me. I'm enjoying my time here and enjoying playing with this team with what's at stake."

Alonso batted just .192 in his first seven games with the Mariners before breaking out Wednesday.

"I think he's been swinging the bat great the last three or four days," Mariners manager Scott Servais said. "He looks like the guy we saw early this year in Oakland."

Alonso wasn't the only standout for Seattle.

Reliever Tony Zych (6-3) got the victory and Marc Rzepczynski earned his first save.

The Mariners brought in Edwin Diaz with a three-run lead in the ninth, but he couldn't close it out.

Diaz walked the first three batters he faced to bring up Manny Machado with the bases loaded.

Machado drove the ball to right-center, with right fielder Martin making a sliding catch to limit the damage to one run on the sacrifice fly.

"That was definitely the play of the game," Servais said. "(Center fielder Jarrod) Dyson has an issue with his groin and is not running his best. Leonys tracked that play."

Said Martin: "Dyson doesn't feel good right now, so I was trying to take care of my guy."

Diaz caught Jonathan Schoop looking at a called third strike for the second out but hit Trey Mancini on a check swing with a 3-2 pitch to re-load the bases. Diaz then hit Mark Trumbo with a pitch as the Orioles closed within a run.

The Mariners summoned the left-handed Rzepczynski to face left-handed-hitting Chris Davis. Rzepczynski struck out Davis on three straight pitches, the last a called strike.

"A couple of those pitches were right down the middle and I got away with it," Rzepczynski said. "I've come in with the bases loaded and two outs plenty of times, but never in the ninth inning. My only other career save was a four-out save. I just tried to go out there and attack."

Both starters, Baltimore's Ubaldo Jimenez (5-8) and Seattle's Marco Gonzales, went just 4 1/3 innings.

Jimenez gave up six runs on eight hits, with one walk and two strikeouts. Gonzales allowed four runs on nine hits, with no walks and one strikeout.

Baltimore's Tim Beckham led off the game with a home run, the second time he has done so in the series. It was Beckham's 17th homer of the season.

The Mariners tied the score in the third, as Mike Zunino led off with a double and scored two outs later on a double by Guillermo Heredia.

Nelson Cruz was hit by a pitch from Jimenez leading off the fourth, and Alonso followed with a 411-foot blast into the right-field seats, giving Seattle a 3-1 lead.

Gonzales struck out the leadoff batter in the fifth, then yielded five consecutive hits as the Orioles took a 4-3 advantage. That included a run-scoring triple by Craig Gentry, the No. 9 batter in the order. Beckham's run-scoring single brought home Gentry with the go-ahead run.

The Mariners responded with three runs in the bottom of the inning to regain the lead.

Jean Segura led off with a single and Heredia was then hit by a pitch. Robinson Cano followed with a run-scoring single, tying it at 4-4.

An out later, Alonso beat a defensive shift by squibbing a run-scoring single to left field. Danny Valencia followed by lining an RBI single to right to make it 6-4.

The Mariners added their final run as Martin led off the sixth with a solo homer off Orioles reliever Richard Bleier.

"One of those games you can look back on seven or eight things during the course of the game," said Orioles manager Buck Showalter, whose team went 4-6 on its 10-game trip and is still in the AL playoff hunt at 59-62. "But you know what, we're headed back to Baltimore. It's been a long trip and we have a chance to roll the dice the last six weeks, and that's what we hope to do -- compete with a chance to play in October. We're still engaged in it."

NOTES: Mariners manager Scott Servais was ejected by first base umpire Stu Scheurwater in the ninth inning for arguing whether Trey Mancini swung at the 3-2 pitch that hit him. ... Mariners CF Guillermo Heredia was hit on the right forearm by a pitch in the fifth inning. He was replaced by Jarrod Dyson in the field in the top of the next inning. ... The Mariners went 2-5 on their homestand, the only seven games they have at Safeco Field this month. ... The Orioles and Mariners are both idle Thursday. The Orioles return home and open a three-game series Friday against the Los Angeles Angels. The Mariners begin a 12-game trip Friday at Tampa Bay. ... Mariners RHP Christian Bergman, designated for assignment Tuesday, cleared waivers and was assigned to Triple-A Tacoma.