SEATTLE -- In need of a pick-me-up after a tough weekend at the plate, the Mariners rode a big homer from Dominic Canzone and a spurt of Chaos Ball en route to a 5-4 win over the Guardians on Monday night, paving the way for a clean and comfortable outing for Emerson Hancock as he stepped into the No. 5 spot in Seattle’s rotation.

Julio Rodríguez had two remarkable catches -- one going back at the warning track and another in the gap running in -- and he nearly had a third at the wall going for a ball that caromed off his glove and went for a homer. The latter ultimately ended Hancock’s night in an otherwise superb outing at T-Mobile Park.

“It starts with pitching with us, and we’re really excited for Emerson Hancock,” Mariners manager Scott Servais said. “That's his first Major League win tonight, and he earned it -- against a team that's been swinging the bat really well.”

Hancock, who assumed the rotation’s final spot when Bryan Woo suffered right elbow inflammation last week, showed no jitters despite pitching on a platform where plenty might persist. Beyond the homer, he surrendered two additional runs, including one that might not have manifested had it not been for an overturned challenge that turned a groundout into a hit-by-pitch.

That third-inning sequence, which saw Ramón Laureano take a sinker off his knuckles halfway through a swing, led to Seattle’s first ejection of the season, with Dylan Moore being removed from the game by first-base umpire Adam Hamari while in the home dugout.

The play was initially ruled a groundout to Hancock, but after a challenge from Guardians manager Stephen Vogt -- who last year was the Mariners’ bullpen coach -- it was ruled a HBP.

The explainer was that, during the action, home-plate umpire Mark Ripperger appealed for a check-swing to Hamari, who ruled that there wasn’t one. That then led the Mariners’ dugout, along the first-base line and within earshot of Hamari, to question how a ball in play that was initially ruled a groundout manifest without a swing at all.

“Guys are fired up, it was a crazy call,” Servais said. “The check-swing, obviously to hit a ball that rolls that far back to the pitcher, you had to have swung, but the umpire saw it differently.”

Immediately after, Hancock surrendered consecutive singles, a run-scoring forceout to Steven Kwan, a sacrifice fly to Andrés Giménez and another single to José Ramírez before escaping the jam. He wound up pitching 5 1/3 innings, beyond the threshold that Servais had hoped.

Though Hancock has been in the organization since being taken with the No. 6 overall pick in the 2020 Draft, Monday marked just his fourth MLB start. Injuries -- the latest a season-ending right shoulder strain last August -- have largely defined his career.

But he was among the more promising storylines in Spring Training, and filling in for Woo -- who began playing catch on Monday -- will be vital, especially this early.

“It kind of felt like a debut all over again,” Hancock said. “Just the pregame, just the hype of how excited I was to get back out there.”

Canzone was another spring standout, but he’s been seeking his timing after going 0-for-8 in the season-opening series. The positive was that he ambushed a 1-1 fastball from Triston McKenzie up and away and sent it 411 feet to left-center for a three-run shot in the second. But he also struck out twice more on offspeed pitches, to bring his season total to six punchouts in 12 plate appearances.

“Just kind of trying to get back on track, being a little bit more aggressive and just getting my swing off,” Canzone said. “Driving the ball that way, that's something that we work on and it's something that we worked on pregame so it's just nice to get a result out of it.”

The Mariners added another key run in the fourth when Luis Urías drew a bases-loaded walk, after Cal Raleigh ripped a 108.6 mph single, Ty France lined one over Ramirez’s head and Canzone reached on a fielding error by first baseman Josh Naylor -- a sequence tying back to Seattle’s efforts of making better swing decisions and getting the ball in play.

However, one decision they’d like to have back was Rodríguez running through a stop sign from third-base coach Manny Acta in the eighth, though a 1-2-3 ninth from Ryne Stanek for his first save as a Mariner wound up overcoming that mistake.