SAN FRANCISCO — This was another major step in the right direction for James Paxton. But there is still work to do.

The Yankees’ left-hander has the opportunity of a baseball lifetime staring him in the face. If he makes the most of it, the Yankees will have the chance to make some noise this season despite all their injury woes.

The Yankees and Giants are renewing some wonderful old acquaintances this weekend, and it began Friday night at Oracle Park. Paxton matched up against Giants legend Madison Bumgarner and both were out of the game after 5²/₃ innings.

Paxton and the Accidental Yankees held a 5-3 lead at the time and even though Zack Britton walked the bases loaded in the seventh, the Yankees held on for the 7-3 victory because Adam Ottavino caught Buster Posey looking at strike three to end the inning. Luke Voit (a triple shy of the cycle) crushed a two-run home run in the ninth.

With the win, Paxton improved to 3-2. His ERA is 3.38. He allowed just five hits, but the Giants managed to squeeze across three runs. He walked two and struck out eight as his pitches varied from 79 mph to 98.

Paxton has the opportunity to put the Yankees’ rotation on his shoulders because of the lat and shoulder injuries to Luis Severino, along with the slippage of Masahiro Tanaka — who produced only one swing and miss in Thursday night’s 11-5 loss to the Angels. For three straight games Tanaka has not had his splitter working. CC Sabathia is giving it his best at age 38 but does not have the tools he once had, and J.A. Happ, at the age of 36, is trying to find ways to win.

So all that leaves a path wide open for Paxton, 30, to lead this rotation.

“I was using my curveball a little bit more, didn’t really have the great cutter tonight,’’ Paxton said.

This first month has been a learning experience for the new Yankee.

“I’ve learned that this is just the same game as anywhere else,’’ Paxton said. “You just got to go out there and compete. I’ve had a lot of fun competing with these guys, it’s a great clubhouse here. We have each other’s backs.’’

Here is the big change.

“I’ve just tried to be aggressive and attack the strike zone as much as I can,’’ Paxton said.

“He’s done everything we’ve asked,’’ pitching coach Larry Rothschild told The Post. “I was confident that he would come around. He knows what he is doing.’’

Paxton got himself in better alignment on the mound, which enabled him to up his velocity with everything moving toward the plate in synch.

Paxton came into the night not having allowed a run over his last 14 innings, but the Giants managed to score their initial first-inning run of the season.

This is a complete turnaround from his first three starts as a Yankee. Paxton knew he had to change his approach both mentally and physically and make the necessary adjustments.

Paxton is challenging hitters up in the zone and Rothschild, even when Paxton was struggling, said the left-hander would turn it around. He just needed a little time to understand what it was like to pitch in New York after so many years in Seattle, including increasing that velocity earlier in the game.

The bullpen blew it for Paxton last time out, but this time the relievers managed to hang on to the lead.

The turning point for Paxton was his eight innings of shutout ball against the Red Sox on April 16 at Yankee Stadium. That did wonders for his confidence and gave him a real taste of what the AL East is all about.

There remains one major question mark with Paxton. Will he be able to up his innings to ace level?

Paxton has never thrown more than 160 innings in a season. Those came last season and Friday night he should have been able to get through six innings against the punchless Giants. He needs to go deeper in games and pile up the innings.

That’s what it will take.

That 200-inning bar is the hurdle he must jump to truly become the Yankees’ ace.