One step from history. One win from tennis immortality — as if Serena Williams weren’t already there.

Williams is onto Saturday’s U.S. Open final — and an opportunity to match Margaret Court’s record of two dozen Grand Slam titles.

She got there with a 6-3, 6-1 rout of Elina Svitolina at Arthur Ashe Stadium on Thursday. It gives her a shot to avenge her controversial loss in last year’s final — and rewrite the record book while she’s at it.

“It’s cool that I’ve been in more finals than anyone (currently) on tour after being pregnant. That’s kind of awesome,” Williams said. “It’s not easy to go through what I did and come back — and so fast. To keep playing to also not be 20 years old — yeah, I’m pretty proud of myself.”

For good reason.

Williams had her trademark power, flashed a rare serve-and-volley game and moved as well as she has since giving birth to daughter Olympia two years ago. The sight of her easily chasing down ball after ball had training guru Mackie Shilstone beaming proudly in the stands.

“On the important moments, she always step up, always brings her best game,” said Svitolina, who’d been expected to test Williams after beating her in the 2016 Olympics. But Williams had a bad shoulder in Rio; Thursday in Flushing, her game and her shoulder were just fine.

Williams broke Svitolina’s first serve on a return down the line to go up 2-0. She opened the next game with an ace and won on love, but the fifth game typified the match.

After falling behind love-40 and facing triple break point, she roared back to win on a passing shot. She cruised the rest of the way, sealing it with a nasty backhand down the line.

“What she does and what she achieved, it’s something unbelievable,” Svitolina said.

Williams improved to 101-12 at the U.S. Open, tying Chris Evert’s mark.

“I don’t think about the numbers, I just come out here and do what I can. Been here for 20 years — and still here,” Williams said. “To be in any club with Chrissy is awesome.”

Now she’s just a win away from joining Court as the only players with 24 Grand Slam singles titles. She’s been stuck one title shy since childbirth.

Over the two years since becoming a mother, Williams is 33-5 in Grand Slam play with four finals berths, but she lost the first three, including last year’s testy loss in Flushing Meadows.

“I’ve had so many chances to pass it and to have a lot more, but it’s cool because I’m playing in an era with so many — five eras with so many amazing players,” Williams said.

“I haven’t really thought much about it, to be honest. I just knew I need to work harder, just do better.”

The only other times Williams has fallen in the final in Flushing (2001 and 2011), she stormed back to win the next year. That bodes well Saturday vs. young Bianca Andreescu, who ran off the last five games to beat Belinda Bencic 7-6 (3), 7-5.

Andreescu, 19, wasn’t even born when Williams won her first Slam here in 1999. But her own rise has been meteoric, from losing in qualifying last year in Flushing to making this final in her first-ever main draw. She’s won 13 straight matches, including last month’s final in Toronto when Williams retired with a bad back.

“It’s never easy retiring for an athlete, especially in the final of a tournament,” Andreescu said. “I told her she’s a beast, she’s going to bounce back. And she did; she’s in the final. So I’m looking forward to facing her again.”