By RONALD BLUM

NEW YORK (AP) — Pete Alonso hit his 53rd home run to break the rookie record Yankees star Aaron Judge set in 2017, and the New York Mets beat the playoff-bound Atlanta Braves 3-0 on Saturday night.

A 24-year-old who debuted on opening day, Alonso launched a 93 mph fastball on a 1-2 count from former All-Star Mike Foltynewicz just to the right of straightaway center field. The solo shot in the third boosted the lead to 3-0 and followed a two-run homer earlier in the inning by light-hitting backup catcher René Rivera.

As Alonso’s 415-foot drive landed in the seats, the Home Run Derby champion raised both arms in triumph while running to first base. Mets teammates came out of the dugout to congratulate him, and the crowd of 32,210 at Citi Field gave a standing ovation to a player nicknamed Polar Bear during spring training by teammate Todd Frazier.

“It’s surreal. It was almost like an out-of-body experience,” Alonso said. “Unbelievable moment.

“This is more than a dream. This is more than fantasy. I can’t put it into words.”

Alonso raised both arms again, tilted his head back and looked skyward as he stood in front of the dugout. Overcome with emotion, he had tears in his eyes when he went to first base in the fourth.

“I was just kind of thinking about all the greats in the game of baseball. I was thinking about guys like Babe Ruth, Ted Williams, guys like Aaron Judge,” Alonso said, “and the fact that I’m ahead of those guys as a rookie, it’s mind-blowing.”

He heads into the final day of the regular season leading the majors in homers, four ahead of Cincinnati’s Eugenio Suárez. No rookie since 1900 has won an outright home run title in the big leagues.

Alonso has already set franchise records for homers, total bases (347) and extra-base hits (85). He has 120 RBIs and 102 runs, becoming the first Mets rookie to reach triple digits in both categories. The home run was his 11th of September.

Steven Matz (11-10) allowed two hits and five walks in six innings, finishing with a winning record for the first time since his first full season in 2016. Jeurys Familia, Brad Brach and Edwin Díaz finished the three-hitter. Diaz struck out two in a perfect ninth for his 26th save in 33 chances, his first save since Aug. 15 — also against the Braves.

Foltynewicz (8-6) gave up three runs and three hits in his final start for the NL East champions before the Division Series against St. Louis or Milwaukee.

An All-Star last year who started the Division Series opener against the Los Angeles Dodgers, Foltynewicz was bothered by elbow discomfort during spring training, was demoted to the minor leagues and made his first four starts for Triple-A Gwinnett. Recalled by Atlanta, he went 2-5 with a 6.37 ERA in 11 outings and got sent down in late June for five more outings with the Stripers.

Foltynewicz had been 6-0 in nine starts since his return on Aug. 6.

Rivera’s home run, on a hanging slider, was his first since Aug. 15 last year for the Los Angeles Angels off San Diego’s Kirby Yates,

PLAYOFF PLANS

Atlanta’s playoff rotation lines up to have left-hander Dallas Keuchel (8-8) start the opener, with Foltynewicz and rookie right-hander Mike Soroka (13-4) likely to follow. Manager Brian Snitker says the order won’t be finalized until Monday at the earliest, and he still isn’t sure whether to include 11 or 12 pitchers on his roster.

“I don’t know if we’re a finished product yet. We’re still young and talented,” Snitker said. “Honestly, I’m not so sure these guys didn’t start the year expecting to do this. Nobody else did. I think they did. Everybody else picked us to finish fourth, I think.”

LOOKING AHEAD

Former Yankees manager Joe Girardi, who may be among the candidates to replace Mickey Callaway if the Mets make a change, was at Citi Field broadcasting for Fox.

SLUMPING

Atlanta 1B Freddie Freeman was 1 for 3 with a walk and two strikeouts, a day after returning from four days off to rest his sore right elbow. Freeman has not homered since Sept. 1 and entered in a 2-for-31 slide.

DONATING

Alonso will donate the 9/11 tribute cleats he wore in a game this month to the 9/11 Memorial & Museum at a ceremony Tuesday.

TRAINER’S ROOM

Braves: OF Ronald Acuña Jr., who hasn’t played since Tuesday because of a tight left hip, will take batting practice for three days starting Monday and will run Wednesday, a day before the Division Series opener. …. OF Ender Inciarte, who last played Aug. 16 because of a strained right hamstring that still causes discomfort, returned to Atlanta to be examined and “he’ll be down for the foreseeable future,” Snitker said. … Utilityman Johan Camargo, out since fouling a ball off his right shin on Sept. 11, also will miss the Division Series. “The one thing that we’ve been bitten by with the injuries is our bench — what was really a strong-looking bench with some guys that we don’t have anymore,” Snitker said.

Mets: OF-INF Jeff McNeil expects to have surgery Tuesday, six days after the ulna bone in his right hand broke when hit by a pitch from Miami’s Josh Smith.

UP NEXT

Soroka (13-4) goes Sunday for the Braves in a tuneup for his playoff start. RHP Noah Syndergaard (10-8) pitches for the Mets.

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