Boston Red Sox’s Sandy Leon, right, celebrates his three-run home run that also drove in Michael Chavis, center, and Jackie Bradley Jr. (19) during the third inning of a baseball game against the Seattle Mariners in Boston on Saturday, May 11, 2019. (AP Photo/Michael Dwyer)

BOSTON — Sandy Leon fouled off an bunt attempt, then hit a three-run homer to cap an eight-run third inning that carried the surging Boston Red Sox over the struggling Seattle Mariners 9-5 on Saturday.

Mitch Moreland started Boston’s comeback from a 4-0 deficit against Félix Hernández (1-4) with a solo homer. The World Series champions won for the 15th time in 21 games following a 6-13 start.

Seattle has lost 14 of 18 and dropped to 20-22, falling below .500 on Friday for the first time since the end of the 2017 season. The Mariners have been outscored 23-6 in the first two games of the three-game series.

Jay Bruce hit a two-run homer and reached 900 RBIs.

Hernández (1-4) allowed seven runs and six hits in 2 1/3 innings. The 2010 AL Cy Young Award winner is 0-4 in seven starts since beating the Los Angeles Angels in his season debut. He became the 36th pitcher to reach 2,500 strikeouts when rookie Michael Chavis took a 92 mph sinker for a called third strike in the second inning.

Rick Porcello (3-3), the 2016 AL Cy Young winner, gave up four runs and five hits — all in the first — in 6 2/3 innings. He is unbeaten in five starts after losing in his first three appearances.

Moreland homered in the second, the ninth home run off Hernández this season.

Xander Bogaerts’ RBI single and Rafael Devers’ two-run singled chased Hernández, in his second shortest start this season. Jackie Bradley Jr.’s two-run single off Roenis Elias put Boston ahead 6-4. With Bradley on first and Chavis creeping down the line from third, Leon fouled off a safety squeeze attempt. Three pitches later, Leon lined a fastball into the first row of Green Monster seats for his first homer since last Aug. 14.

Seattle scored four times in a four-pitch span with two outs in the first. Dan Vogelbach and Domingo Santana hit RBI doubles and Bruce followed with his 12th homer, a drive into Boston’s bullpen.

BIG THREE

Boston had a nine-run third inning last Saturday in a 15-2 rout of the White Sox that included 10 straight hits, one shy of the major league record set by Colorado Rockies against the Chicago Cubs on July 30, 2010

FILLING IN

Seattle bench coach Manny Acta was the acting manager for the second straight game. Manager Scott Servais was attending his daughter Victoria’s graduation from Mississippi. Servais is expected back Sunday.

DEBUT

Mariners 2B Shed Long made his major league debut, bouncing to second on the first pitch he saw and going 0 for 2 with a walk. Asked what advice he gave him, Acta said: “Don’t let all aura of Fenway Park take away from the moment — embrace it. It’s a special opportunity, know that you’re going to be here for a long time. Take a deep breath.”

TRAINER’S ROOM

Mariners: Acta said INF Dee Gordon was still day-to-day after getting hit on the right wrist by Yankees LHP J.A. Happ on Thursday. “He’s available to pinch run,” Acta said. “He’s got to figure out how to slide and not put his hand down.”

Red Sox: Manager Alex Cora said LHP David Price will throw a bullpen on Sunday. Price has not pitched since May 3 due to left elbow tendinitis).

UP NEXT

Mariners: LHP Marco Gonzales (5-1, 3.08 ERA) was slated to start the series finale.

Red Sox: Boston’s starter for Sunday was not clear.