NEW YORK -- Brandon Belt was in a daze.

Hours before the Giants embarked to Queens to face the Mets, Belt learned that his maternal grandmother, Margaret Peterson, had died from COVID-19. It was a crushing loss for Belt, who called Peterson one of his biggest supporters throughout his baseball career.

Belt texted his wife and parents before the game to let them know he was struggling emotionally, but his family reminded him that Peterson would want him to go out and do the best he could. So he did.

Belt honored his late grandmother by going 4-for-5 with two home runs and three RBIs to help power the Giants’ 8-0 rout of the Mets on Tuesday night at Citi Field.

The 33-year-old first baseman opened the scoring with a 431-foot shot that bounced off the Home Run Apple in straightaway center field in the first inning and then teamed up with LaMonte Wade Jr. to crush back-to-back shots off Mets right-hander Tylor Megill in the fourth. Belt’s seventh career multi-homer game allowed him to reach 19 home runs on the season, a new career high.

“It’s been a pretty tough day,” Belt said. “I’ve kind of been in a daze all day. I was just glad I could come out here and do that for her. I just wanted to dedicate the rest of the season to her as well. She was a huge supporter of mine, so this really does mean a lot.”

Mike Yastrzemski also went deep as part of the Giants’ four-homer night, becoming the first player to hit 20 home runs for San Francisco this season.

The Giants now lead the Majors with 191 home runs, four ahead of the Blue Jays, who have the benefit of playing in a league with the designated hitter. The Giants scored their first six runs of the night via the long ball before Brandon Crawford capped a four-run rally with an RBI single off Trevor Williams in the fourth.

Crawford’s base hit knocked in the Giants’ first non-homer run since the 11th inning of their loss to the Mets at Oracle Park on Wednesday. All nine of the Giants’ runs against the A’s this weekend also came on home runs.

The steady diet of homers provided ample run support for rookie left-hander Sammy Long, who worked 5 1/3 scoreless innings to earn his second career Major League win and his first since June 20. Long, who started in place of the injured Anthony DeSclafani, allowed only three hits while walking one and striking out four. He also supplied one of the Giants’ 15 hits on the night, lining a single to left field in the second to pick up his first career MLB hit.

The Giants improved to 81-44, the best record in the Majors, though they also took a pair of hits when Buster Posey and Crawford were forced to depart with left knee discomfort and lower back tightness, respectively. Manager Gabe Kapler said the Giants’ veterans are day to day and would be reevaluated prior to Wednesday’s game.

Though he was playing with a heavy heart, Belt found a bit of emotional catharsis in his first at-bat against Megill in the first inning.

“It was a pretty emotional at-bat,” Belt said. “It was pretty emotional the whole game, but it was one of those things where I had to stop and go be by myself for a little bit. Just kind of take it all in and know that there was something higher at play there.”

Belt credited Peterson and his grandfather with helping to get his baseball career off the ground, as they frequently provided financial support to ensure that he could attend showcases when he was in high school. After Belt developed into a two-time World Series champion with the Giants, he would sign cards for his grandmother, who would distribute them amongst her friends at church and at her assisted living facility.

“She didn’t raise me or anything, but I think we had a really good relationship,” Belt said. “She was always proud to brag about me to her friends. She and my grandfather really helped me early on in my baseball career. They played a huge role in getting me where I am today. It’s a tough day and it’s part of life. I think I can honor her best by playing to the best of my ability for the rest of the season.”