Cronenworth singled home the go-ahead run in the sixth inning for the Padres, who hit three solo homers off Walker Buehler and beat the Dodgers 5-4 on Monday night.
"If I didn't know before today there was a rivalry, I definitely do know now," said Cronenworth, whose hit gave ace Chris Paddack his first career win against Los Angeles.
"It's fun to play in those type of games. I never played in major league playoff baseball but if I had to guess, that was like it. It was fun. Guys were talking back and forth. It was great."
Cronenworth also turned in several nice plays at first base, where he made his fifth start. First baseman Eric Hosmer is on the injured list with a stomach ailment.
"Just three so-so pitches that they took advantage of," Buehler said.
Paddack (2-0) allowed three runs and five hits in six innings, struck out five and walked none. His previous three starts against Los Angeles were at Dodger Stadium last year as a rookie. He went 0-1 in those games.
Buehler gave up three home runs for just the second time in his career. He left after five innings with the score tied at 3 after yielding three hits while striking out three and walking three.
"I thought overall, very positive. We got the pitch count up, got him through five," Dodgers manager Dave Roberts said.
"I just don't think that he had his command that he will have. It's his second start of the year. So, he's going to be fine and I think now we can kind of loosen the reins more his next turn and win a baseball game his next turn."
Brusdar Graterol (0-2) relieved Buehler to open the sixth and permitted a single by Manny Machado, who advanced on Tommy Pham's grounder. Cronenworth singled to bring in Machado for a 4-3 lead. Cronenworth later scored on Austin Hedges' two-out single, the first time the catcher reached safely this season.
Padres manager Jayce Tingler said Cronenworth was "super impressive. That's from the get-go, I thought he was really good in the box. Even the at-bats he didn't get hits in, I just thought he was a threat up there. He looked comfortable, to be able to lace a line drive over shortstop. And then it was two or three kind of game-saving defensive plays. ... He was outstanding tonight."
Cronenworth made his major league debut on July 26. He was obtained with Pham in an offseason trade with Tampa Bay that sent Hunter Renfroe to the Rays.
It was the first meeting of the year between the seven-time defending NL West champion Dodgers and the Padres, who think they're built for success in the pandemic-shortened 60-game season. Los Angeles went 13-6 against San Diego last year.
"This is a very talented offensive club," Roberts said about the Padres. "They're playing well, they've got a lot of confidence, so this was no surprise."
Joc Pederson homered to left-center on Paddack's first pitch, his first of the season and his 21st career leadoff homer.
Grisham homered to right with one out in the bottom of the inning, his fourth. Myers homered to right-center with two outs it the fourth, his third, for a 2-1 lead.
"Just not enough strikes, not enough good counts for me," Buehler said. "Got to get in the zone more and start getting in better counts."
Tatis tied it with a shot to right with two outs in the fifth, his third. Tatis hit a tying solo homer in the ninth inning at Colorado on Friday night. Pham later hit a three-run drive and the Padres won 8-7.
Dodgers: OF Mookie Betts was out of the lineup for the first time this season with a finger injury sustained during an at-bat Sunday at Arizona. Roberts said the swelling in the finger was still substantial. "Hopefully we'll see how he feels tomorrow and see if we can get him in there," Roberts said.
Dodgers: RHP Dustin May (0-0, 2.35 ERA) makes his third start of the season. He is 0-2 with a 3.46 ERA and nine strikeouts in four career appearances against San Diego.
Padres: RHP Dinelson Lamet (1-0, 1.80) is scheduled to make his third start.
More AP MLB: https://apnews.com/MLB and https://twitter.com/AP-Sports
How empty ballparks would have changed MLB history -- and could alter games this October
Think you don't make a difference as a fan? As these classic postseason moments prove, you have a lot more power than you realize.
Ranking the pitching staffs of every potential MLB playoff team
With a new format and compressed schedule, pitching this postseason is tough to forecast. But we did it anyway.
Giants eye playoff push in finale with Rockies
The San Francisco Giants can bolster their playoff chances while also formally eliminating the visiting Colorado Rockies from contention when the National League West clubs meet for a final time on Thursday afternoon.
Cards, Brewers making playoff push with 5-game series
The visiting Milwaukee Brewers and St. Louis Cardinals continue their battle for playoff berths when they open their five-game series Thursday.
Alomar, Indians riding high into White Sox finale
Sandy Alomar Jr. has guided the Cleveland Indians to a 24-18 record this season while serving as acting manager in place of Terry Francona, who has persevered through a spate of health issues but appears on track to join the club for the playoffs.
Dodgers' Buehler makes mound return against A's
Even after clinching their division title, as well as the best record in the National League, the Los Angeles Dodgers might be playing one of their most important games of the season at home Thursday against the Oakland Athletics.