SEATTLE -- Unflappable pitcher Hisashi Iwakuma burst into a rare smile in the moments that followed his first no-hitter on Wednesday afternoon, as his Seattle Mariners teammates engulfed him in celebration.

It was the 34-year-old starter's first noticeable crack of emotion on a day when he threw 116 pitches to beat the Baltimore Orioles 3-0.

Seattle manager Lloyd McClendon, on the other hand, was a bundle of nerves for a good part of the afternoon.

"I'm just glad it's over with," McClendon said after Iwakuma pitched the fifth no-hitter in franchise history and the first in the American League since August 2012, "because I've had to pee since the fifth inning."

An over-the-shoulder catch from third baseman Kyle Seager in foul territory and a game-ending grab by center fielder Austin Jackson ended a tense ninth inning and allowed Iwakuma and the Mariners to breathe a sigh of relief.

"To be honest, I never thought I would accomplish a no-hitter," Iwakuma said through interpreter Antony Suzuki. "I can't find words to express my feelings. Extremely happy."

Iwakuma became the 291st pitcher in baseball history, and the first in the American League since teammate Felix Hernandez did it in 2012, to throw a no-hitter. Three walks, the first two of which came in the fourth inning, stood in Iwakuma's way of a perfect game.

"I was having a feeling from the fifth inning because he was making so many quality pitches," said catcher Jesus Sucre, who caught a no-hitter for the first time in his two-year career. "Amazing."

Iwakuma (4-2) said he had never gotten past the fifth inning of a game, even during 11 professional seasons in Japan, without giving up a hit. He tried to ignore the possibility Wednesday but started to feel the weight of the moment after Seager's catch near the wall in foul territory for the first out of the ninth inning.

"When Seager made that great play, it made me think I could throw a no-hitter," Iwakuma said.

Seager was asked about the importance of the play and joked that he doesn't often get asked about catches made in foul territory. He added that making an over-the-shoulder catch in that situation added to the pressure of the moment.

"It's not ideal," Seager said. "I'd rather be under the ball, but I'm not fast enough to get there. But I'll take it. As long as he doesn't ask me to do it again, I'll take it."

Iwakuma needed just five pitches to get through the ninth inning, the final of which came on a first-pitch fastball that Baltimore right fielder Gerardo Parra drove into center field.

"When he first hit the ball, I thought it was the first hit, and I was like, 'Oh, no,'" Iwakuma said. "Then I saw Jackson raise his glove in the air, and I was like: 'Yes!'"

Jackson chuckled at the notion that the ball might have dropped in for a heart-breaking hit.

"In that situation, in any situation, really, that ball doesn't touch the ground," Jackson said.

Iwakuma threw the fourth no-hitter of the season, joining the San Francisco Giants' Chris Heston, the Washington Nationals' Max Scherzer and the Philadephia Phillies' Cole Hamels. It was the fifth no-hitter in Mariners history.

The last three no-hitters in the American League have been pitched by the Mariners, with Hernandez tossing a perfect game at Safeco Field on Aug. 15, 2012, and six pitchers combining on a no-hitter on June 8, 2012. National League pitchers had thrown 15 no-hitters in between Hernandez's perfect game in 2012 and Iwakuma's outing Wednesday.

"The outs are tougher," McClendon said when asked why it has taken so long for the AL to follow Hernandez's no-hitter. "The lineups are deeper. In the American League, the DH's are animals. Those are tough outs."

The only other Japan-born pitcher to throw a no-hitter was Hideo Nomo, who did it twice -- with the Los Angeles Dodgers in 1996 and as a member of the Boston Red Sox in 2001.

The Mariners jumped out to a 2-0 lead on designated hitter Franklin Gutierrez's RBI double and second baseman Robinson Cano's RBI single on consecutive at-bats in the third. Sucre added an RBI single in the fourth.

Iwakuma retired the first nine batters before leadoff hitter Manny Machado drew a leadoff walk in the top of the fourth. Baltimore first baseman Chris Davis added a two-out walk in that inning, but Iwakuma got out of the jam by striking out designated hitter Jimmy Paredes.

Iwakuma rolled from there, retiring 10 in a row before issuing a leadoff walk in the eighth. His pitch count reached 112 before Orioles catcher Caleb Joseph grounded into an inning-ending double play to carry the no-hit bid into the ninth.

"I was aware of it, obviously," Iwakuma said, "but I kind of felt it real deep in my heart in the ninth inning. Just focusing on one hitter at a time, and I'm glad I got it done."

The Orioles (57-56) had just one runner get past first base, stranding only two runners for the game. But first baseman Chris Davis said the pressure of the no-hit possibility wasn't a factor in the late innings.

"In that situation, a three-run ball game, you know you just need one baserunner on," Davis said. "Unfortunately, we couldn't do it. You have to tip your hat. (Iwakuma) was throwing well out there.

"Nobody likes to get no-hit, shut out, anything like that, but a loss is a loss. You move forward."

Iwakuma is in his fourth season with the Mariners after establishing himself as one of the top Japanese pitchers. He has battled minor injuries for much of the past two seasons and was making his 11th start of 2015 on Wednesday.

Baltimore starter Kevin Gausman (2-4) allowed three runs off six hits over seven innings. He struck out a career-high eight while walking two.

"Gausman was really good today," manager Buck Showalter said.

Just not as good as Iwakuma.

"So awesome," Sucre said. "That was a great moment. Kuma did a tremendous job today."

NOTES: Orioles C Matt Wieters (tight hamstring) was not in the lineup. Wieters, who had to leave Tuesday's game in the third inning, told the Baltimore Sun before the game that he was feeling better and hoped to be available this weekend at Oakland. ... Seattle DH Nelson Cruz (stiff neck) was held out of Wednesday's game but should be available when the Mariners return to action Friday. ... Baltimore RHP Chris Tillman (bruised right triceps) is scheduled to make his next start on Monday at Oakland. Tillman took a line drive off his triceps in Tuesday's first inning but was able to stay in the game. ... The Mariners' 10-inning win over Baltimore on Tuesday night clinched a piece of baseball history. It marked the first time on a day in which at least 15 games were played that all 15 home teams won.