CINCINNATI >> Wilmer Flores was never himself last season. He injured his knee early. He tried to play through the pain. He ended up with the worst season of his career, one that ended with him undergoing a season-ending Tenex procedure on his birthday.

Still, the Giants’ brass maintained faith. They believed that with a clean bill of health, Flores could get back to the form he exhibited in 2023, the year he hit a career-high 23 homers. On Opening Day, that faith was rewarded in the form of a go-ahead, three-run home run in the ninth inning that delivered a 6-4 win over the Cincinnati Reds at Great American Ball Park Thursday afternoon.

One game does not make a season, but if for just a day, San Francisco’s conviction in Flores is paying dividends.

“He’s built for those moments,” said left fielder Heliot Ramos, the Giants’ 19th consecutive Opening Day outfielder in the past 19 years. “The fact that it was him was super cool to see, bouncing back from last year and all the injuries.”Added manager Bob Melvin: “He’s usually better when there’s more money on the line.”

For there to be money on the line, the hitters ahead of Flores needed to cash in on their own trips to the plate.

The Giants entered the ninth inning trailing 3-2, their only offense deriving from Ramos’ two-run, opposite-field home run off Hunter Greene to conclude an 11-pitch at-bat. Aside from that swing, San Francisco’s offense was mostly flat, striking out 14 times and mustering three hits through eight innings. With one out in the ninth, the Giants’ offense showed signs of life.

Jung Hoo Lee set the table by drawing his second walk of the day, then advanced to third on Matt Chapman’s single to right field. Ramos struck out following Chapman’s hit, bringing the Giants down to their last out, but Patrick Bailey drove in Lee with a single just beyond the outstretched glove of second baseman Matt McClain. Bailey tying the game set the stage for Flores to untie it.

Prior to the game, Flores told shortstop Willy Adames that he’d never hit a home run on Opening Day. With one swing, that achievement has been crossed off the bucket list.

Closer Ian Gibaut hung Flores a middle-middle sweeper, and Flores promptly sent it into the left-field bleachers. Not only did Flores give the Giants the lead, but he kicked off a cacophony of boos. The fan who caught Flores’ home run ball threw it back on the field with such vigor that the ball ended up in the infield, rolling past Cincinnati’s Elly De La Cruz.

“He’s always been a clutch guy,” Melvin said. “A lot of walk-offs in his career. The bigger the situation, the better he’s been.”

“In 2023, Wilmer was our best player, by far,” said starter Logan Webb, who allowed three earned runs over five innings with three walks. “Last year, you could obviously see he was in some pain and dealing with some knee stuff and struggling. It’s great to see it. We saw it all spring. ... Wilmer’s a pro’s pro. You just know he’s always going to have good at-bats and he did it at the end.”

Before Flores’ game-changing swing, the at-bat of the afternoon belonged to Ramos. And in a vacuum, Ramos’ 11-pitch duel with Greene may have been more impressive.

When Ramos stepped to the plate in the fourth, San Francisco was trailing Cincinnati 3-0, unable to generate any offense against Greene. Through three innings, Greene had seven strikeouts. Greene was one strike away from putting a fourth straight zero on the board; Ramos proceeded to get the Giants back in the game.

With Lee on first after drawing a walk, Ramos got into a 3-2 count and fouled off five straight fastballs. Ramos expected Greene to mix in a breaking ball at some point, but Greene kept hurling heaters. On the 11th pitch he saw, Ramos deposited a fastball into the right-field bleachers.

In Flores’ opinion, the pitch Ramos homered on — a down-and-away fastball clocking in around 99 mph — was the toughest pitch of the entire battle. At 344 feet, Ramos’ first homer of the year benefitted from the dimensions of Great American “Small Park.”

“It’s the confidence that I can hit the ball the other way,” Ramos said. “I’m not even going to lie, the splash (hit) gave me a lot of confidence last year, too. I always knew I had that pop. I just needed to make it better and polish it.”

Ramos has historically struggled against right-handed pitchers, entering the day with a career .656 OPS against righties compared to .956 OPS against lefties. He’ll likely see time in leadoff when a left-hander is on the mound. Despite his struggles against righties, the 25-year-old invites the challenge.

“Lefties, I know I can hit them. Obviously, lefties are going to get me out. They’re pitchers, too. They eat, too,” Ramos said. “But I’ve been wanting to face righties. I’ve been wanting to make that a point, for sure.”

With those swings from Flores and Ramos, the team, as a whole, has made quite a point, too.

The Giants enjoyed an objectively great spring. They went 21-6. They were third in ERA and OPS. They excelled in every facet of the game.

They believe they can make the playoffs. They believe they can make noise, even in a stacked NL West. A win on Opening Day, one that gives Buster Posey a 1-0 record as president of baseball operations, was a step in that direction.