BOSTON (AP) — With a hand on his heart and a quick glance to the sky, Stephen Piscotty made an emotional salute to his late mother and helped the Oakland Athletics win in his return to the lineup.

Hours after being reinstated from the bereavement list and flying cross-country to join the A's in Boston, Piscotty hit a towering home run out of Fenway Park in his first at-bat Tuesday night as Oakland beat the Boston Red Sox 5-3.

"It was pure joy. It's been an emotional week," said Piscotty, whose mother, Gretchen, died May 6 after a one-year battle with amyotrophic lateral sclerosis, also known as Lou Gehrig's Disease. She was 55.

Piscotty had missed four games to be with his family as they grieved the loss and celebrated Gretchen's life. He slowly made his way around the bases, then after rounding third placed his right hand over his heart and patted it with a glance to the sky.

"Coming around third, I just immediately started thinking about my mom and kind of put my hand over my chest like she would do," Piscotty said.

It was a touching moment for anyone aware of what Piscotty and his family had been through.

"To hit a home run in his first at-bat like that, there's something in the air. Probably Gretchen," Oakland manager Bob Melvin said. "It was like a walkoff. The guys just embraced him when he got in the dugout."

Melvin actually gave Piscotty the option to sit out Tuesday, when he got a ride to the airport around 3:45 a.m. in California for a flight to Boston. Piscotty, who said he still felt like he was on West Coast time, declined the option.

"He wanted to play. He's on little sleep, a lot of adrenaline," Melvin said. "I know he was really- looking forward to that first at-bat. To be able to do what he did tells you a little seething about him."

Piscotty drove an 0-2 pitch from Eduardo Rodriguez out to left in the second inning. Piscotty's third homer of the season was his only hit of the night and put the A's up 3-0. Matt Chapman and Mark Canha had two RBIs apiece for the A's, who took the first two games of the series against the struggling Red Sox.

Andrew Benintendi homered for Boston and Mitch Moreland finished with a pair of doubles for the Red Sox, who have struggled since their torrid start to the season.

Daniel Mengden (3-4) pitched six solid innings for Oakland, scattering eight hits and holding Boston to two runs — one earned — and struck out three. Blake Treinen finished it off for his eighth save of the season and Oakland improved to 4-1 against Boston this season.

"We haven't been able to put them away," Boston manager Alex Cora said. "They're young and it seems like they're turning a corner. Whatever they're doing over there is pretty good."

Rodriguez (3-1) took his first loss of the season after getting roughed up in the first few innings. Oakland had six hits through the first three innings, starting with back-to-back singles by Marcus Semien and Chad Pinder to start the game. Both scored on a double by Chapman, who drove a pitch from Rodriguez over the head of Mookie Betts in right field.

Rodriguez was pulled after throwing 98 pitches in five innings.

"They were swinging a lot and getting a lot of foul balls," Rodriguez said. "I was getting a lot of like 0-2 counts and then going to 3-2. I need to work at putting guys out quicker than that."

Benintendi's solo homer in the fifth pulled Boston back within 3-2, but the A's tacked on a pair of runs in the eighth.

The game was scheduled to begin at 7:10 p.m., but didn't get under way until 8:52 p.m. because of heavy rain and lightning.

TRAINER'S ROOM

Athletics: To make room on the roster for Piscotty, Oakland optioned RHP Kendall Graveman to Triple-A Nashville.

Red Sox: Placed RHP Carson Smith on the 10-day disabled list Tuesday with a dislocated pitching shoulder, which he injured during a tantrum Monday night. Smith was upset after Khris Davis led off the eighth inning with a home run to put Oakland up 6-4. ... The Red Sox also recalled LHP Bobby Poyner from Triple-A Pawtucket.

UP NEXT

Athletics: RHP Trevor Cahill (1-1, 2.25 ERA) is expected to get the start after being reinstated from the 10-day disabled list with an impingement in his pitching elbow.

Red Sox: LHP Chris Sale (3-1, 2.17) is coming off a no-decision despite tying a career high with 15 strikeouts while pitching nine innings Friday at Toronto.