ST. LOUIS -- Asked what he liked most about Randal Grichuk's approach during his at-bat in the bottom of the ninth inning Sunday night, St. Louis Cardinals manager Mike Matheny didn't hesitate.

"I liked when the ball hit the grass," Matheny said.

Grichuk's two-out RBI single to left-center field scored Jose Martinez with the winning run as St. Louis handed the Cubs a 4-3 Opening Night loss in Chicago's first game as defending World Series champions.

After coughing up a 3-0 lead in the top of the ninth when Willson Contreras cracked a three-run homer off closer -- and eventual winner -- Seung Hwan Oh, the Cardinals concocted a winning response off reliever Mike Montgomery.

Martinez drilled a one-out, pinch-hit double off the right-center-field wall, and that was followed by the first no-pitch intentional walk in major league history to Yadier Molina. Stephen Piscotty looked at a third strike for the second out, but second baseman Kolten Wong drew St. Louis' eighth walk of the game on a full-count pitch.

Grichuk then ended a 3-hour, 33-minute struggle with the second walk-off hit of his career -- both against Chicago.

"He didn't try to do too much," Matheny said of Grichuk. "You watch how the ball jumps off his bat, even when he backs off a hair."

It was Grichuk who gave the Cardinals what appeared to be insurance in the eighth when he lined a two-run homer through the rain into the bullpen in right-center off Pedro Strop. But Oh, who maneuvered out of a bases-loaded, one-out jam in the Cubs' half of the eighth, blew the save with the help of a play not made.

After plunking Ben Zobrist to start the inning, Oh fanned Addison Russell and appeared to get a potential second out from Jason Heyward's chopper to first. However, Matt Carpenter bobbled the ball and then threw late to Wong covering first for what was ruled an infield hit.

Contreras followed up with a 414-foot blast to left, stunning most of a crowd of 47,566, the third-largest regular season audience in Busch Stadium III history.

"I told Strop, 'Don't worry, we got it.' One swing changed the game," Cubs second baseman Javier Baez said. "You can't win them all, but we'll battle all nine innings."

Chicago's battle in its first game as a world champ in 108 years wasn't very successful most of the night. Carlos Martinez shut the Cubs down for 7 1/3 innings in his first Opening Night start, touching 100 mph with his fastball and attracting 15 swings and misses with his changeup.

Martinez whiffed 10 and walked none before Baez's single in the eighth drove him off the mound after 105 pitches, 68 of them strikes.

"I might have had more adrenaline than before, because I have never had this opportunity," Martinez said. "But I've never had that kind of focus before."

"He was hitting his spots," Baez said of Martinez. "Great pitching, great movement."

Cubs starter Jon Lester wasn't bad, either, although he was extended to 102 pitches in five-plus innings as St. Louis hitters worked counts and grinded out at-bats in a manner their Central Division rivals were known for during last year's curse-chasing championship.

Lester gave up seven hits and a run, walking two and fanning seven. St. Louis was 0-for-7 against him when batting with runners in scoring position, fanning six times.

The only run until the bottom of the eighth came in the third when Carpenter's sacrifice fly scored Dexter Fowler, making his Cardinals debut after playing the last two years in Chicago.

It looked as if Martinez and Oh would make that run stand until plot twists defined the last two innings. The final one, coming off the bat of Grichuk, enabled St. Louis to avoid a potentially brutal season-starting setback.

"You had the home crowd and all the excitement that goes into Opening Day," Matheny said. "Every win is big. ... This is exactly what we hoped would happen."

NOTES: This was the first time St. Louis opened a season at home under manager Mike Matheny. The last time the Cardinals started a season at home was 2011, when they lost 5-3 to San Diego. ... Chicago opened its second straight year without a rookie on the roster. The Cubs started 15 of the prior 19 seasons with a rookie on the 25-man roster. ... Cubs manager Joe Maddon needs just 19 wins to become the eighth active skipper to reach 1,000.