San Diego scored twice in the second inning off Jacob Misiorowski, who opened his first career postseason start with a 104.8 mph pitch.
Xander Bogaerts, Ethan Salas and Luis Campusano singled in succession, with Campusano driving in the first run. Jake Cronenworth brought in the second on a fielder's choice.
Misiorowski held hitters to a .157 average this season, the lowest figure ever recorded by a major league starter, lower than Pedro Martinez's .167 in 2000.
How to watch
Padres at Brewers, NLDS Game 1
Saturday, Oct. 3, 8:30 p.m. ET / 7:30 p.m. CT / 5:30 p.m. PT
American Family Field, Milwaukee
TV: FS1
Spanish: FOX Deportes
Streaming: FOX One
Radio: WTMJ 620 and TUDN in Milwaukee, KWFN 97.3 and XEMO 860 in San Diego, ESPN Radio nationally
National League games are on FOX and FS1 this round. American League games are on TBS and truTV. The Wild Card round was on NBC and Peacock.
FS1 requires a package that includes it, and is carried on YouTube TV, Hulu Live, Fubo, Sling and DirecTV Stream.
Lineups
San Diego: Fernando Tatis Jr. RF, Dustin Harris LF, Manny Machado 3B, Ty France 1B, Jackson Merrill CF, Xander Bogaerts SS, Ethan Salas C, Luis Campusano DH, Jake Cronenworth 2B.
Milwaukee: Jackson Chourio LF, Brice Turang 2B, William Contreras C, Jake Bauers 1B, Christian Yelich DH, Cooper Pratt SS, Luis Lara RF, Garrett Mitchell CF, Joey Ortiz 3B.
San Diego is starting both catchers, with Salas behind the plate and Campusano at designated hitter. Gavin Sheets stays on the bench for a third straight game. Left-handed hitters batted .114 against Misiorowski this season.
Misiorowski
Misiorowski led the majors in ERA at 1.80, strikeouts at 252, WHIP at 0.80 and opponents' average at .157.
The .157 is the lowest on record for a starting pitcher. The 0.80 WHIP is third behind Martinez and Walter Johnson.
A year ago he had lost his rotation spot after a rough second half as a rookie and barely made the postseason bullpen. He threw 12 innings across three relief appearances against the Cubs and Dodgers, allowing two earned runs with 16 strikeouts and a 0.83 WHIP.
He threw 5 1/3 innings against St. Louis in the regular-season finale, which lines him up on five days' rest.
Robbie Ray
Ray starts for San Diego at 13-8 with a 3.59 ERA. He has a 2.82 career ERA against Milwaukee with a .193 average against.
The choice is about handedness. Milwaukee ranked first in the majors in wRC+ against right-handers this season and 13th against left-handers.
Ray arrived at the deadline and has been uneven, but San Diego won each of his last three starts.
Nick Pivetta starts Game 2. Michael King is also available.
The teams have met before
San Diego won four of six against Milwaukee this season, including a three-game sweep in August in which the Brewers blew leads in the seventh, eighth and eleventh innings.
San Diego's pitchers held Milwaukee to 3-for-28 with runners in scoring position in that series.
Milwaukee then went to Dodger Stadium, won three of four and finished with 103 wins, a franchise record and the best mark in baseball. The Brewers are the first team to win the National League Central four years in a row.
Both teams went 18-6 in September.
Who to watch
Fernando Tatis Jr. hit .289 with 25 home runs and 38 stolen bases. Manny Machado bats third. Xander Bogaerts, from Oranjestad, Aruba, plays short.
Ethan Salas catches. The 20-year-old Venezuelan became the youngest player in major league history to catch a postseason game in the Wild Card Series against the Cubs.
Jackson Chourio leads off for Milwaukee. William Contreras, the Venezuelan catcher, hits third. Christian Yelich is the designated hitter. Jake Bauers is having a career year at 30.
Cooper Pratt starts at shortstop. Milwaukee signed him to an eight-year, $50 million extension after his debut this season.
Walker Buehler is on the paternity list for San Diego. Randy Vasquez replaces him on the roster.
New ownership in San Diego
Jose E. Feliciano and Kwanza Jones completed a $3.9 billion purchase of the Padres, unanimously approved by owners on Aug. 17. Jones became the first Black woman to own a major league franchise.
A.J. Preller remains general manager.
The series schedule
Game 1 — Saturday, Oct. 3, 8:30 p.m. ET, Milwaukee
Game 2 — Sunday, Oct. 4, 4 p.m. ET, Milwaukee. Nick Pivetta starts for San Diego.
Game 3 — Tuesday, Oct. 6, 9:30 p.m. ET, San Diego
Game 4 — Wednesday, Oct. 7, 10 p.m. ET, San Diego, if necessary
Game 5 — Friday, Oct. 9, 4:30 p.m. ET, Milwaukee, if necessary
All on FS1. The winner plays in the National League Championship Series beginning Oct. 11.
Neither team has won a World Series.
The rest of Saturday
Tampa Bay beat New York 1-0 in ALDS Game 1. Drew Rasmussen allowed one hit over eight innings with 10 strikeouts, tying the Rays postseason franchise record. Jonathan Aranda homered off Gerrit Cole for the only run.
Chicago beat Cleveland 3-0. Munetaka Murakami hit a two-run homer off Parker Messick.
Los Angeles beat Atlanta 5-3. Teoscar Hernandez, Kyle Tucker and Max Muncy homered for the Dodgers.