SEATTLE -- Wei-Yin Chen made a stunning play to prevent the Mariners from scoring a first-inning run, then he did his part to make sure Seattle didn't come close to scoring again Thursday night.

After using his glove to scoop and throw the ball for a out at home plate in the first, the Orioles left-hander didn't allow another runner past first base. He threw eight innings of five-hit ball in Baltimore's 4-0 win over the Mariners.

"He took us as far as he could," Baltimore manager Buck Showalter said after Chen's 109-pitch effort. "That's about as good as he's pitched."

The closest Seattle got to a run came in the first inning, when leadoff hitter James Jones tried to score from third base on a slow chopper hit by second baseman Robinson Cano in front of the mound. Chen scooped the ball with his mitt and tossed it home in one motion, recording the second out of the inning when catcher Caleb Joseph tagged out Jones at the plate.

"I saw the runner was going, so I just did what I needed to do to get the ball to the plate," Chen said through an interpreter. "I had a lot of practice on those in spring training, and that's the result of all that practice."

Chen and reliever Darren O'Day combined on the shutout, while Baltimore (56-45) got all the offense it needed in the third inning. The Orioles rode a four-run third inning, highlighted by Delmon Young's three-run homer, to the victory.

Chen (11-3) won his fourth consecutive start and held an opponent without a run for only the second time this season.

"My slider and curveball worked well today, and I had good command of my fastball," Chen said. "That's why I was able to pitch so well today."

Young provided the big blow with a three-run homer in the third inning. He hit the first pitch he saw from Seattle starter Hisashi Iwakuma over the left field fence for a 4-0 lead.

"(Iwakuma) elevated his slider," Mariners manager Lloyd McClendon said, "and you can't do that against a guy who hits the slider so well."

Iwakuma only had one bad inning, but it was enough to saddle the right-hander with his first loss in almost a month. Iwakuma (8-5) gave up four runs, all of them coming in the third inning, on seven hits in seven innings. He did not allow a walk, extending his streak to 35 2/3 consecutive innings without issuing one.

Since his previous loss on June 25, Iwakuma was 3-0 with a 1.57 ERA through four July starts heading into Thursday.

The Mariners, who acquired veteran slugger Kendrys Morales from the Minnesota Twins earlier in the day but had yet to welcome him to the team, were held to five hits. Seattle (53-49) has scored just three runs during a three-game losing streak.

"We're not swinging the bats well right now," McClendon said. "We just have to keep grinding it out. When you don't hit, you don't look good."

The Orioles had eight hits, five of which came in the third inning.

In the third inning, the first four Baltimore batters reached base. Third baseman Ryan Flaherty and catcher Caleb Joseph collected singles before right fielder Nick Markakis drove in the first run with a single. Young then hit the first pitch from Iwakuma over the left field fence to open up a 4-0 lead.

The seldom-used Young, who went 2-for-4, collected his first home run and first multiple-hit game of July.

The Mariners had a chance to get on the board first, when Jones walked to lead off the bottom of the first inning and moved to third base on a stolen base and groundout.

After he was retired on Cano's grounder, McClendon challenged the call at the plate, which was upheld. Afterward, the Seattle manager was scratching his head about the new rule that forbids catchers to block the plate. Joseph's foot was in the way when Jones attempted to make a headfirst slide, but the catcher was not called for obstruction.

"I'm a little puzzled with that," McClendon said. "(Joseph) didn't have the ball, and he was in front of the plate. To me, that's blocking the plate."

NOTES: The Mariners made a pre-deadline deal, sending RHP Stephen Pryor, a hard-throwing reliever, to Minnesota to reacquire DH Kendrys Morales. The 31-year-old Morales hit 23 homers and had a team-high 80 RBIs for Seattle last year but opted not to re-sign with the team. He played 39 games for the Twins after being signed in June, hitting .234 with one home run and 18 RBIs. ... Orioles 3B Manny Machado (back spasms) was out of the lineup for the third game in a row. ... Seattle placed INF Willie Bloomquist (knee contusion) on the 15-day disabled list, selected SS Chris Taylor from Triple-A Tacoma and recalled DH Jesus Montero from Tacoma. The Mariners had a roster spot available after optioning RHP Taijuan Walker back to Tacoma after his Wednesday start. ... Baltimore acquired OF/INF Jimmy Paredes from Kansas City for future considerations. Paredes was subsequently optioned to Triple-A Norfolk. Paredes, 25, was hitting .305 for Triple-A Omaha.