DENVER — The St. Louis Cardinals picked up a win before a pitch was even thrown when reserve outfielder Jose Martinez captured a playful, pregame staredown with Colorado reliever Carlos Estevez.

Too bad for the Cardinals that didn’t count in the standings. They sure could’ve used it.

Nolan Arenado hit a grand slam, German Marquez pitched five solid innings for his first major league win and the Rockies slowed the Cardinals’ playoff chase with an 11-1 victory on Wednesday.

The Cardinals, who had won four straight, entered the day tied with New York and San Francisco atop the NL wild-card standings. The Mets and Giants both played later.

Arenado broke open the game in the second with his NL-leading 39th homer of the season. His fourth career slam made it 6-1.

It’s a pitch that simply caught too much of the plate.

“Stayed straight,” starter Luke Weaver said. “For it to flatten out at such a big moment right there is disappointing.”

Weaver (1-4) was roughed up by the Rockies, surrendering seven hits and six runs in two innings. Before this game, the right-hander had allowed 12 earned runs in his last seven starts combined.

The Cardinals had some early momentum when that standoff went their way just after the anthem.

Here’s how it unfolded: Estevez and Martinez stood near their dugouts — with their baseball cap over their heart — and refused to back down until the other moved first.

Estevez blinked first and made a winner of Martinez, who celebrated before retreating to the dugout. Estevez said manager Walt Weiss pulled him in out of fear of being ejected.

“It’s not fun to have one less bullpen guy,” Estevez explained.

Martinez was going to see this thing through to the end — no matter the consequences.

“The umpire asked me, ‘Why you do that?’ I’m like, ‘When you’re a rookie and a big league guy asks you to stand up there, I stand up there,'” said Martinez, who had a pinch-hit single in the seventh. “The most important thing is we have fun and the fans enjoyed it.”

This was a memorable day for Marquez (1-0), who made his first big league start after three appearances out of the bullpen. He allowed one run and struck out three.

At 21 years, 212 days, Marquez was the second-youngest pitcher in Rockies’ history to earn his first win, the team announced. The youngest was Jamey Wright (21-206).

“A great pitching performance from the kid today,” Weiss said. “It’s easy — easy velocity. Very effortless.”

The hard-throwing Marquez was acquired in January as part of the deal that sent outfielder Corey Dickerson to Tampa Bay. Marquez pitched a majority of the season for Double-A Hartford, where he was chosen as the pitcher of the year in the Eastern League.

Marquez worked his way out of several dicey situations against the best road team in baseball. He allowed his only run in the second, when Jeremy Hazelbaker led off with a double and later scored on Kolten Wong’s sacrifice fly.

The Cardinals took two of three from Colorado during a series in which their starting pitchers were brilliant at the plate. Carlos Martinez, Adam Wainwright and Weaver went a combined 4 for 4 with two doubles and six RBIs. Weaver had a single in his only plate appearance.

DJ LeMahieu got two hits and drove in two runs to raise his average to .351. He holds a slight lead over Washington’s Daniel Murphy in the NL batting race.

TRAINER’S ROOM

Cardinals: OF Matt Holliday (broken right thumb) is hoping to take live batting practice Friday at Wrigley Field before the Chicago Cubs series. … C Yadier Molina had the day off.

Rockies: Third base coach Stu Cole sat out another day after being hit in the head by a ball that caromed off another during batting practice Tuesday.

THIS & THAT

Rockies catcher Tom Murphy had a three-run homer as part of a five-run seventh. … Arenado’s grand slam gives him 128 RBIs this season, which leads the majors.

UP NEXT

Cardinals: After a day off, RHP Mike Leake (9-10, 4.54 ERA) opens a three-game series Friday in Chicago. RHP Jake Arrieta (17-7, 2.96) goes for the Cubs.

Rockies: RHP Tyler Chatwood (11-9, 4.13) takes the mound Thursday to begin a four-game series in Los Angeles against the Dodgers. Chatwood is 7-1 with a 1.77 ERA in 11 road starts this season.