ST. LOUIS -- Back in April when the season started, it was easy to expect the Pirates' season-ending trip to Busch Stadium meaning something for both Pittsburgh and the St. Louis Cardinals.

Instead, all Pittsburgh can do when it closes the season is play the role of spoiler against a Cardinals team trying to make its sixth consecutive National League playoff appearance.

St. Louis starts the Friday night series opener fresh off the year's most controversial win, a 4-3 decision Thursday night over the Cincinnati Reds that was decided by Yadier Molina's two-out RBI double in the bottom of the ninth inning.

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Molina's one-hop liner shouldn't have scored Matt Carpenter, though, because the ball hit off signage beyond the left field wall. It should have been a ground-rule double, but third base umpire Scott Barry ruled the ball in play and the Reds didn't challenge fast enough after the fact.

"Biggest win of the year," Cardinals manager Mike Matheny said, "and tomorrow night's the biggest game of the year. Can't wait."

St. Louis (83-76) is two games behind the New York Mets (85-74) for the NL's top wild-card spot and a game in arrears of the San Francisco Giants (84-75) for the second spot.

The Giants close the season with a three-game series against the Los Angeles Dodgers, while the Mets finish with three at Philadelphia.

The Cardinals will have the matchup advantage in the opener against the Pirates as St. Louis right-hander Carlos Martinez (15-9, 3.15 ERA) will face raw but talented Pittsburgh right-hander Tyler Glasnow (0-1, 4.91).

Martinez is coming off a 3-1 loss Sunday night at the Chicago Cubs that saw him work six innings and give up two runs on six hits and four walks while fanning six. Martinez is 3-5 with a 4.01 career ERA against the Pirates, and 1-2 this season in three starts.

Glasnow will make his fourth career start. His first occurred July 7 in St. Louis, where he pitched decently for 5 1/3 innings but lost 5-1 as Adam Wainwright stifled Pittsburgh for seven innings. The hard-throwing Glasnow can touch the mid to upper 90s with his fastball but has experienced command issues at times.

The Pirates (78-81) reached the playoffs the past three seasons, but they fell victim to injuries and inconsistent pitching this year. They will have to sweep the series to avoid their 21st losing season in 24 years.

Pittsburgh will be without left fielder Starling Marte (back) for the weekend and might be without shortstop Jordy Mercer (forearm) as well.

"We're going to play all the men that are capable of playing," Pirates manager Clint Hurdle said. "Marte has been unplugged. Mercer might not be able to go. You saw a couple of throws he made across the diamond (Thursday). ... That's basically all he's got."

Pittsburgh leads the season series 9-7, having won five of the seven games in St. Louis. The Cardinals are 35-43 at Busch Stadium, clinching their first losing mark at home since 1999.

The Saturday game will match Pirates right-hander Chad Kuhl (5-4, 4.25) against a pitcher to be determined. St. Louis will use Wainwright (13-9, 4.67) in Sunday's regular-season finale opposite Ryan Vogelsong (3-7, 5.00).