SEATTLE -- That was the J.A. Happ the Toronto Blue Jays expected to see this season.

The veteran left-hander pitched six scoreless innings to earn his first victory of 2017 as the Blue Jays defeated the Seattle Mariners 4-0 Sunday afternoon at Safeco Field.

"He looked like the old guy, really, a jumping fastball and much better command," Toronto manager John Gibbons said of Happ, who was a 20-game winner last year. "He didn't use a whole lot of other (pitches), he normally doesn't anyways. I think that was a step in the right direction, and it answered a lot of questions for me."

Happ (1-4) spent six weeks on the disabled list this season due to left elbow soreness. The outing at Safeco Field was his third start since returning to action.

"I felt more like myself today," Happ said. "I had more life on my fastball than in the first two outings."

The Mariners put runners in scoring position in each of the first four innings against Happ, but he got out of the jams unscathed.

"I felt like we had (Happ) on the edge the first couple of innings, but just didn't push him over the edge," said Mariners manager Scott Servais, whose club went 0-for-10 with runners in scoring position and stranded 11 on base.

Happ retired the side in order his final two innings. He allowed six hits, walked one and struck out eight.

"A couple of times he got out of the zone, but boom, he was able to make adjustments," said Blue Jays third baseman Josh Donaldson, who homered and drove in three runs.

Six Blue Jays relievers combined for three scoreless innings to complete the shutout, allowing three hits. Roberto Osuna got the final out for his 16th save of the season.

Mariners starter James Paxton took his first loss of the year.

Paxton (5-1), a left-hander from Ladner, British Columbia, allowed four runs on eight hits in four innings. Paxton was also making his third start since coming off the disabled list, as he was out most of May with a left forearm strain.

The Blue Jays got to Paxton in the first inning. Kevin Pillar led off with a double down the left field line, and Donaldson followed with a two-run homer to right field, his eighth of the season.

The Blue Jays struck again in the fourth, as Pillar doubled with two outs and Donaldson drove him home with a single to right. Donaldson advanced to second on a walk and scored on Morales' single to left, making it 4-0.

"They really grinded through some at-bats to get Paxton's pitch count up," Servais said. "Donaldson was on him all day, geared up for him."

Seattle got another runner into scoring position in the seventh against the Toronto bullpen, as Ben Gamel led off with a single off Jeff Beliveau and stole second. Ryan Tepera struck out Taylor Motter and pinch hitter Jarrod Dyson, then got Mitch Haniger to fly out to right field to end the inning.

Robinson Cano led off the eighth with a single off Aaron Loup. Joe Smith came on to get back-to-back groundouts as Cano advanced to third, and Danny Valencia struck out to end the threat.

The Mariners put two runners on in the ninth with two outs, forcing Gibbons to turn to Osuna. The closer got Haniger to fly out to right field to cap the victory.

Mariners right-hander Emilio Pagan pitched four hitless innings of relief, allowing one walk and striking out five.

NOTES: Mariners RF Mitch Haniger returned after being on the disabled list since April 26 with a strained right oblique. Haniger went 0-for-4 with a walk. To make room on the roster, Seattle optioned OF Boog Powell to Triple-A Tacoma. ... The Blue Jays are off Monday before starting a two-game series Tuesday at home against Tampa Bay. RHP Marco Estrada (4-4, 4.04 ERA) is scheduled to start for Toronto against Rays RHP Jake Odorizzi (4-3, 3.59). ... Seattle opens a four-game series Monday at Minnesota. RHP Yovani Gallardo (2-6, 6.26) is set to go up against Twins LHP Adalberto Mejia (1-1, 4.18).