SAN FRANCISCO – Buster Posey didn’t let a 3-0 pitch pass in the first inning against the Dodgers’ Walker Buehler. Instead, he popped a two-run, opposite-field homer to open the Giants’ 4-0 victory in Game 1 of the National League Division Series at Oracle Park on Friday night.

The home run bounced off the top of a fountain tower beyond the right-field porch and into McCovey Cove, where it was quickly scooped up with a fishing net by an eager boater on the water. Because it didn’t hit water on the fly, Posey was robbed of the first “Splash Hit” by a right-handed batter since the Giants’ downtown stadium opened in 2000.

The aggressiveness on a 3-0 pitch is part of an adjustment in Posey’s longtime hitting approach. But the feelings Posey brought into the game were the same jitters he felt long ago. It was good he blasted those out of his system.

“There are definitely butterflies, but I think those can be helpful, kind of heighten your focus,” Posey said. “And, yeah, Buehler's tough. He doesn't give you a lot to hit sometimes, and fortunately there, I got a pitch I could handle and got the barrel on it.

“And the dang column kept me from a Splash Hit.”

Posey is well-decorated, with three World Series rings, the last coming in 2014. But Posey had waited even longer between postseason homers. It was his first since Game 4 of the 2012 World Series, when he went deep off of the Tigers’ Max Scherzer.

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Also, Posey put himself in the Giants’ history book as the team’s oldest player with a postseason homer -- 34 years, 195 days -- since Barry Bonds (38 and 94 days) and Shawon Dunston (39 and 219 days) went deep in Game 6 of the 2002 World Series against the Angels.

Posey’s homer was part of a theme -- veterans experiencing more glory.

Kris Bryant, who won a World Series with the Cubs in ’16, drove a full-count pitch off Buehler to left field to open a 3-0 lead in the seventh. It was his third hit of the night, matching the total he had over his final 17 regular-season at-bats.

Brandon Crawford, twice a champ with the Giants, watched Alex Vesia strike out the first two batters in the eighth, then powered the first left-on-left delivery from Vesia out to center.

That all four of the Giants’ runs came via home runs shouldn’t come as that much of a surprise. The club led the NL with 241 homers this season and those accounted for 49.5 percent of their runs scored.

With two out in the first, Posey continued the regular-season trend.

Buehler had strike-one issues in the first. He walked leadoff man Tommy La Stella, who moved to third on a Wilmer Flores grounder and a Brandon Crawford fly ball. Buehler had a base open, but decided to venture into Posey’s strike zone for the first time.

Posey made him pay with his fifth career postseason homer.

Turns out homers on 3-0 counts are a new phenomenon for Posey. According to Inside Edge, Posey has four career homers on such counts. This was his second since Aug. 27. It also was the first homer on a 3-0 count in Giants postseason history, dating back to when full pitch-count data is available (1988).

The 3-0 homer is even rarer in Buehler’s world. He had not given up a homer on that count in 103 career regular-season games (93 starts) and 11 postseason games (all starts).

“Buster's been in this game a long time,” Buehler said. “They obviously have trust in him to swing 3-0 -- just a mistake heater [95.8 mph, up, outside and eventually out]. Obviously, it was in an area that he can drive the ball, and just not a great throw.”

Dodgers manager Dave Roberts said, “I don't think anybody in the ballpark was surprised that [Posey] was swinging 3-0. He does that frequently.”

Posey is doing it more than frequently. He’s swung at 3-0 pitches 33 percent of the time this year -- by far the highest rate of his career.

“It's just on the attack from pitch one, trying to get something that you can drive -- and not necessarily letting the count dictate that approach,” Posey said.

His approach illustrates the buy-in that veteran Giants are exhibiting under Giants manager Gabe Kapler, who preaches a “selective aggression” philosophy.

“Buster’s home run was a great way to set the tone early,” said Crawford, who homered in the same postseason game as Posey for the first time in their careers. “He has a slow heartbeat. He doesn’t really change from the regular season to the postseason. Not at all surprised at him being able to take out a 3-0 pitch and take a good swing at it.”