It's the eighth loss in nine games for the Padres, who were held to one run or less for the 23rd time this season and eighth time in June.
"He has a good, live, young arm," San Diego manager Bud Black said of Elias. "He threw some secondary pitches as the game went on when he was behind the count, which I think helped him."
Elias (6-5) — winner of three of his last four — stymied the Padres for seven innings, allowing three hits while striking out six and walking none. San Diego sent the minimum three batters to the plate in five innings.
Rene Rivera provided the only San Diego run with a homer to left in the second inning to give the Padres a short-lived 1-0 lead.
Jesus Montero quickly put the Mariners on top in the bottom of the frame with a two-run home run. It was Montero's first home run in the big leagues since May 8, 2013, and the former top catching prospect was making his first career start at first base.
Montero was suspended 50 games for his connection to the Biogenesis performance-enhancing drug investigation last year and began the season at Triple-A Tacoma before being recalled on June 12.
"I really appreciate the opportunity that the Mariners are giving me again," Montero said. "It's really hard for me, what I was going through last year — very tough year. Little by little, was in Triple-A working hard to be here and they gave me an opportunity again, and I feel really happy that they were paying attention to me."
Robinson Cano hit a two-run home run off San Diego starter Eric Stults (2-9), who allowed four runs, six hits and a walk in five innings. The left-hander struck out five, but had trouble finding the strike zone consistently and needed a season-high 102 pitches.
"I felt like my stuff was better today, I just haven't had the results the last few outings I would like to see," Stults said.
Despite the unfortunate result, Black has been more impressed with Stults the last few times.
"Right out of the chute I thought his stuff was good — 90 mph fastballs, a good changeup, working aggressive, pitching fast," Black said. "The tempo between pitches improved. The second inning elevated the pitch count a little bit, but I thought his stuff was fine. They stressed him a little bit and pitch count was elevated, but he battled and competed like he always does."
The Padres bullpen was unable to keep the game close as Kyle Seager hit a two-out, bases-loaded double down the line in left field in the seventh. Seager leads Seattle with 47 RBIs, the most by a Mariner through 71 games since Raul Ibanez had 49 in 2007.
NOTES: The teams travel to San Diego for another two-game set. Seattle RHP Felix Hernandez and San Diego RHP Andrew Cashner are slated to pitch in the opener on Wednesday. ... Black said INF Jedd Gyorko (plantar fasciitis) is not close to returning from the 15-day DL, despite being eligible to be reinstated on Friday. Gyorko, though, may be able to shed his walking boot on Friday.