SAN FRANCISCO -- The Giants knew Patrick Bailey would help them win plenty of games with this Gold Glove-caliber defense behind the plate. But lately, the second-year backstop has been showing that he can have just as big of an impact with his bat.

Bailey cranked a three-run home run off Pirates closer David Bednar in the bottom of the ninth inning to snap a scoreless tie and lift the Giants to a dramatic 3-0 walk-off win in Friday night’s series opener at Oracle Park.

Bailey’s second career walk-off homer -- the other coming on Aug. 13, 2023, vs. the Rangers -- capped a suspenseful ninth for the Giants, who also saw Camilo Doval narrowly escape a huge jam in the top half of the inning. The Pirates loaded the bases with one out, but Doval managed to preserve the tie by coaxing a 1-2-3 double play from former Giants prospect Bryan Reynolds.

San Francisco finally broke the stalemate after Michael Conforto walked and Matt Chapman singled to put a pair of runners on for Bailey, who ended the game by blasting an elevated fastball from Bednar over the right-field arcade for his third home run of the year.

“Not only is he swinging it well, he’s obviously had some feel for the dramatics here recently,” manager Bob Melvin said. “It showed up again for him right now. He’s playing great baseball, both behind the plate and at the plate.”

Bailey, 24, entered Friday with the second-most Defensive Runs Saved (4) among Major League catchers, trailing only the Mariners’ Cal Raleigh, but he’s also been a force at the plate, hitting .297 with an .881 OPS over his first 20 games of the season.

“I feel like my swing is in a much better spot than it was last year,” Bailey said. “One thing this year I tried to build was my confidence at the plate. I felt like I proved to myself last year that I could do it at this level, even with the struggles at the end. So that was my biggest thing this year. Just going up confident every time, no matter what I’ve been going through.”

Bailey’s late-game heroics ensured that the Giants didn’t squander a phenomenal outing from rookie left-hander Kyle Harrison, who struck out seven over six scoreless innings in his best start of the year. Harrison allowed only five hits and walked none, lowering his ERA to 4.09 on the season.

“He was great,” Bailey said. “It’s probably the best I’ve seen him this year.”

No Major League starter has been as reliant on his fastball as Harrison, who threw his heater 68% of the time over his first five starts of the year. He didn’t have his best fastball at the beginning of his outing, but he managed to compensate by incorporating more of his offspeed pitches early on.

Harrison still leaned primarily on his four-seam fastball, which accounted for 54% of his pitches, but he mixed in more of his changeup (29%) and breaking ball (17%), resulting in a season-high 13 swinging strikes. He said he was particularly encouraged by the results he got with his breaking ball, which generated three of his seven strikeouts.

“That was something I worked my butt off in my last ‘pen on, just trying to get back to kind of the normal version of myself,” Harrison said. “The slider felt great today, and I was able to use it. That’s something that I really wanted to have in the past, but knowing now that I can be able to fix it from outing to outing is pretty cool.”

Despite his dominance, Harrison didn’t end up factoring into the decision, as his effort was matched by right-hander Quinn Priester, who also spun six shutout innings for the Pirates.

The Giants appeared to have something stirring against Pittsburgh’s bullpen in the eighth, when Nick Ahmed reached on a one-out single, but the momentum stalled after Ahmed was picked off by left-hander Aroldis Chapman.

Jung Hoo Lee and Wilmer Flores followed with back-to-back walks to put a pair of runners on for Jorge Soler, but Gold Glover Ke’Bryan Hayes made a nice backhand play on Soler’s 103.3 mph liner to the left side and then stepped on third for an inning-ending forceout.

While they were unable to break through in the eighth, the Giants came back to deliver the decisive blow in the ninth thanks to Bailey.

“We were all hyped in there,” Harrison said. “Patty’s a man.”