OAKLAND -- The Giants were two outs away from watching their lead in the National League West shrink to a mere half-game over the Dodgers, but LaMonte Wade Jr. saved the day by coming off the bench to deliver one of the biggest home runs of the year.

Wade crushed a go-ahead two-run shot off closer Lou Trivino in the ninth inning to lift the Giants to a 6-5 comeback win over the A’s on Saturday at the Coliseum, evening the Bay Bridge Series and maintaining San Francisco’s 1 1/2-game division lead with 39 games left to play.

The Giants trailed, 5-4, entering the top of the ninth, but Brandon Belt started the rally by drawing a walk off Trivino. Manager Gabe Kapler then decided to send up the left-handed-hitting Wade to pinch-hit for Darin Ruf, a move that paid off when Wade hooked a 1-1 fastball just inside the right-field foul pole for his 16th home run of the year.

“It’s not easy to come off the bench after you’ve been sitting there for three-and-a-half hours and put a good swing on a ball like that,” Belt said. “But it’s something that we as a team have been able to do really well this year. It’s especially hard for a young player like LaMonte, but he’s shown up at-bat after at-bat, late in the game. He’s been huge for us.”

It was Wade’s first career pinch-hit homer, a feat made even more impressive given the unique circumstances visiting hitters face while playing at the Coliseum. The visiting batting cage is located out in center field and isn’t easily accessible once games start, making it more difficult for hitters to prepare to come off the bench in late-inning situations.

Wade said he leaned on the game plan provided by hitting coaches Justin Viele and Donnie Ecker, who advised him to look for something up.

“Before that at-bat, JV and Eck were in my ear telling me kind of what areas to look for, what pitches to look for, so I give all credit to them,” Wade said. “Luckily, I was able to run off the plan.”

Wade, 27, has emerged as a revelation for the Giants this year, batting .251 with an .854 OPS while serving as the club’s primary leadoff hitter against right-handed pitching. He’s shown a penchant for coming through in big spots, too. He entered Saturday hitting .474 (9-for-19) with runners in scoring position and two outs, the second-best clip in the National League behind the Padres’ Fernando Tatis Jr. (.481).

Did Belt have any words for Wade following the latter’s clutch blast?

“I didn’t have anything to say to him,” Belt said. “I think he knows he’s a badass.”

Closer Jake McGee took over in the bottom of the ninth and worked a scoreless inning to seal the win for the Giants, who snapped their two-game mini skid to improve to 79-44, the best record in the Majors.

It was a huge swing game for the Giants, who have maintained their grip on first place in the tightly contested NL West since Memorial Day, yet still face a difficult path ahead as they try to fend off the surging Dodgers, who have now won nine in a row with the help of top Trade Deadline acquisitions Max Scherzer and Trea Turner. 

“We don’t expect the Dodgers to go away, but I don’t think we’re going to go away, either,” Belt said.

Kris Bryant, Belt and Ruf also homered to help the Giants overcome sloppy defense, a squandered eighth-inning rally and another shaky start from Kevin Gausman, who has struggled to regain the dominant form he showed in the first half. The 30-year-old right-hander gave up five runs (two earned) over 3 2/3 innings and departed with San Francisco trailing, 5-2, but the Giants managed to pull within one in the seventh after Belt and Ruf went back-to-back off A’s reliever Andrew Chafin.

Gausman logged a brilliant 1.73 ERA over his first 18 starts of the year, but he hasn’t looked the same since the All-Star break, posting a 5.17 ERA over his last seven outings. He’s completed six innings only once in the second half and couldn’t get out of the fourth against the A’s, who forced him to throw 82 pitches in one of his shortest starts of the year. 

“I definitely haven’t been as sharp as I was early in the season,” Gausman said. “My split is still really good, but I feel like it hasn’t had that extra little bite towards the end. Whereas usually I get a swing-and-miss, maybe I’m getting more foul balls. The book is out on me. I think guys know what they’re going to get. If I’m not on, they can do a good job of fouling pitches off.”

Gausman’s regression only adds to the Giants’ rotation concerns, as their depth is already being tested by injuries to Johnny Cueto (right flexor strain) and Anthony DeSclafani (right ankle discomfort). Cueto returned to his native Dominican Republic this week following the death of his mother-in-law, but he’s been throwing bullpens and could be ready to come off the injured list next week at New York. 

DeSclafani played catch at the Coliseum prior to Saturday’s game, but his ankle still didn’t feel great while pushing off. He’s tentatively scheduled to throw a bullpen session on Sunday, but Kapler said the Giants will be ready to “read and react” if DeSclafani’s ankle doesn’t show enough improvement in the next day.