CINCINNATI -- New Giants president of baseball operations Buster Posey was used to experiencing Opening Day jitters during his playing days, but he felt a different set of emotions as he prepared to take in his first opener as an executive on Thursday.

“I don’t have near the butterflies that I had as a player,” Posey said. “I was telling [manager Bob Melvin] just a minute ago that probably I’ll go up to the booth pretty early and just take in the pageantry of Opening Day. I never did that as a player, really, just because I was hyper-focused on the game. I’m excited to do that.”

Posey ultimately got a front-row seat to a dramatic ending at Great American Ball Park, as Wilmer Flores crushed a go-ahead, three-run home run to cap a four-run rally in the top of the ninth inning that lifted the Giants to a 6-4 comeback win over the Reds. The victory was San Francisco's first when trailing through eight innings on Opening Day since April 10, 1968, against the Mets.

San Francisco was down, 3-2, before Jung Hoo Lee walked and Matt Chapman singled to put runners on the corners. Patrick Bailey later lined a two-out RBI single up the middle to tie the game. That brought up Flores, who followed with a three-run shot out to left field to give the Giants their first lead of the game.

“It feels good helping the team right away,” Flores said. “I was talking earlier to [Willy] Adames. I said, ‘I have never hit an Opening Day homer.’ And it happened.”

Situational hitting wasn’t the Giants’ strong suit last season -- they ranked 24th in the Majors after hitting .234 with runners in scoring position -- but they were determined to get better with men on base this spring and saw those efforts pay off with their late rally on Thursday.

“It took to the ninth to get there, but just some tenacious at-bats again in big spots,” Melvin said. “We talked a lot about the two-out hitting. In the spring, it was more base hits. That was a homer. Just huge that Flo came up with it, too. Not only is it good for him, it’s good for us. Just a lot of good things came from this game to be able to come back late.”

It ended up being quite a memorable gift for Posey, who also celebrated his 38th birthday on Thursday -- and enjoyed his own memorable moment at Great American Ball Park in 2012.

“Buster is just a winner,” right-hander Logan Webb said. “I’m excited to keep going with him. He’s 1-0 as the president. It’s a good day for him.”

Webb made his fourth consecutive Opening Day start for the Giants, though he didn’t factor into the decision after giving up three runs on six hits over five innings. The 28-year-old struck out five, but he also uncharacteristically issued three walks, including back-to-back free passes that set up Jeimer Candelario’s two-out RBI single in the bottom of the first.

The Reds extended their lead to 3-0 on Candelario’s two-run single in the third before the Giants finally broke through against Cincinnati flamethrower Hunter Greene in the fourth.

Heliot Ramos -- who became the Giants’ 19th Opening Day left fielder in their past 19 seasons -- won an epic 11-pitch battle against Greene, fouling off five consecutive upper 90s fastballs before driving a 98.7 mph heater out to the right-field corner for a two-run, opposite-field shot that cut the Reds’ lead to 3-2.

“It’s almost as big as Flo’s,” Melvin said. “That was just huge for us. He hits a two-run homer, and now makes it 3-2. But he made [Greene] throw a bunch of pitches, took a little wind out of his sails, too. The next thing you know, he’s out of the game after five. That at-bat was epic. It really was.”

Greene struck out eight and held the Giants to only three hits before departing the game, but San Francisco managed to come alive against right-hander Ian Gibaut, who couldn’t shut the door after hanging a sweeper that Flores banged out to left for the decisive hit of the game in the ninth.

It was an encouraging performance from Flores, who endured a career-worst offensive season while dealing with a nagging right knee injury in 2024, but is already showing the type of production he can deliver when healthy.

“We have faith in him,” Melvin said. “We saw some really good swings this spring. A healthy Flo is just going to be great for our lineup. To be able to do it in the first game and in dramatics like he typically does -- he’s usually better when there’s more money on the line, and that was huge for him.”