Lynn pitched two-hit ball into the seventh inning and the Cardinals beat the Milwaukee Brewers 9-3 on Sunday, taking two out of three games in the series.
It was the third career start for Lynn (1-0), who played a key relief role during the Cardinals' championship run last season. The 24-year-old right-hander was added to the rotation after Carpenter went on the disabled list with a nerve ailment in his throwing shoulder this spring.
"It's still early, so hopefully I can build off what I did today and keep pitching well," Lynn said. "Hopefully it gives us confidence that with Carp out for the time that he's out, we can still win ballgames, and they have confidence in me."
Ryan Braun hit his first home run of the year for the Brewers, a solo shot with the game well out of reach in the ninth.
"No matter who's healthy and who's not, they'll find a way to put together five starters who can consistently keep them in games," Braun said.
Beyond Corey Hart's solo homer -- his third home run in two days -- the Brewers couldn't muster much of anything when Lynn was in the game.
Manager Mike Matheny said the Cardinals aren't the same team without Carpenter, but Lynn's performance was just about the best they could hope for under the circumstances.
"We know what (Carpenter) brings to this team," Matheny said. "But when the game deals you what it deals you, you hope somebody steps up."
Lynn said he's comfortable as a starter because he has been one for most of his career.
"Relieving was fun and I enjoyed it because I got to pitch in a lot of big situations and big games," Lynn said. "That's always fun, as a competitor you enjoy those situations, enjoy those challenges. I see this as a new challenge."
Lynn gave up one run and struck out eight, a career high, while walking only one in 6 2/3 innings. He also picked Braun off first base to end the first and singled in the fourth for his first career hit.
"I got lucky, I guess," Lynn said.
Randy Wolf (0-1) threw 108 pitches in five innings for the Brewers, giving up three runs and nine hits with a walk and seven strikeouts.
Matheny made several lineup changes for Sunday's game, starting Tyler Greene at second base, Matt Carpenter at first, Tony Cruz at catcher and Robinson in center field. Even without a few of their regular players, the Cardinals managed to give Wolf some trouble.
"That does take a lot off of the long haul of the season, being able to have those days where you can throw that lineup out there and know they're going to be able to put up some runs," Matheny said.
Matt Holliday gave the Cardinals a 1-0 lead in the first when he doubled to center and Rafael Furcal scored from first on a high throw home by Rickie Weeks. The Cardinals added another run in the fourth, when Furcal delivered a two-out RBI single.
Wolf gave up another run in the fifth on an RBI single by Freese, but he limited the damage by striking out Robinson with runners on first and second to end the inning.
Hart then homered off Lynn in the bottom of the fifth. Beltran homered off reliever Marco Estrada in the seventh, giving the Cardinals a 5-1 lead.
With Milwaukee trailing 6-1 in the eighth, Alex Gonzalez hit an RBI double to cut the deficit to four.
Robinson had to bargain with the fan who caught the ball to get it back as a souvenir. Although the fan was asking for more, they settled on a ball autographed by some of the Cardinals' veteran players.
"Hopefully, he was happy with that," Robinson said, holding the ball in his hand. "But I really appreciated that he gave it up."
Milwaukee's Norichika Aoki singled as a pinch hitter in the eighth for his first career hit, then scored on Gonzalez's double. ... Furcal had his third three-hit game of the season.