BOSTON — Rookie Michael Chavis hit a grand slam, Xander Bogaerts had three hits and Andrew Benintendi drove in three runs for Boston on Monday night to lead the Red Sox to a 10-8 victory over the Toronto Blue Jays.

Boston batted around for five runs in the first inning against starter Trent Thornton (3-7) and then sent 10 batters to the plate in the third, scoring five more.

Rick Porcello (7-7) gave up four runs and eight hits in six innings, striking out two. Brandon Workman pitched the ninth for his fourth save.

Four of the first five batters reached safely against Thornton before Chavis hit a 3-2 pitch 421 feet over the Green Monster in left-center to make it 5-0. It was his 16th homer, and the first grand slam of his career.

Toronto scored two in the second on Billy McKinney’s homer and two more in the third to make it a one-run game. But Rafael Devers hit a two-run single, Bogaerts added an RBI base hit and Benintendi drove them both in with a double off the Monster down the line.

Thornton, who threw six shutout innings in his previous start, allowed five runs on five hits and three walks while getting just four outs for Toronto, which has lost six of eight.

LATE RALLY

The Blue Jays scored four in the eighth against reliever Ryan Brasier.

After Randal Grichuk grounded out to start the inning, Justin Smoak hit a ground-rule double into the Toronto bullpen, Danny Jansen singled in one run and McKinney singled him to third. Brandon Drury hit a sacrifice fly, and then Eric Sogard had his third hit of the game, a bunt single.

Devers tried to catch McKinney rounding second, but hit the runner in the spikes, and the ball rolled into center field. Matt Barnes relieved Brasier and gave up an RBI single to Freddy Galvis that made it 10-8 before Lourdes Gurriel Jr. flied out to end the inning.

BUSY NIGHT

Devers had another error at third base, on Drury’s grounder in the second, throwing the ball over the first baseman’s head and into the dugout. But he made up for it in the fifth, when he slid to stop Gurriel’s sharp grounder with his backhand and the ball popped into the air.

He waited for it to come down, barehanded it and threw to first just in time to get the runner.

TRAINER’S ROOM

Blue Jays: 3B Vladimir Guerrero Jr. got the night off to rest.

Red Sox: Manager Alex Cora said 1B Mitch Moreland “swung the bat really well” in a simulated game against Nate Eovaldi. Moreland will face Brian Johnson in a simulated game Thursday and could be activated by the weekend series against Baltimore. … Eovaldi is expected to go on a rehab assignment Wednesday or Thursday.

UP NEXT

Blue Jays: Pitcher TBD; Game 2 of the four-game series is at 7:05 p.m.

Red Sox: RHP Andrew Cashner (9-3) will make his first start for Boston since he was acquired Saturday from the last-place Baltimore Orioles.

“This is the World Series champs. It’s a chance to help these guys get to where they want to go,” he said before the game. “I’m definitely looking forward to the race. It’s something I haven’t been in, really.”