PITTSBURGH -- Mike Matheny sat back in his chair and sighed.

"What time is it? Two o'clock in the morning," the St. Louis Cardinals manager said.

It wasn't that late but the Cardinals had to work hard Monday night to get one step closer to their straight National League Central title.

Reserve first baseman Mark Reynolds hit a two-run home run to cap a three-run ninth inning as the Cardinals snapped a scoreless tie and beat the Pittsburgh Pirates 3-0.

The Cardinals (99-58) increased their division lead to four games over the Pirates (95-62). Both teams have five games remaining and St. Louis can wrap up the title with a win Tuesday night in the second game of a three-game series.

"It's pretty amazing when you think about it but we have 99 wins and we still haven't clinched the division," Cardinals starting pitcher Lance Lynn said. "This is how tough our division is. Every game, it seems, is a dogfight, especially when we play the Pirates. It's a great win for us."

Pirates closer Mark Melancon (3-2), who leads the major leagues with a franchise-record 51 saves, started the ninth and gave up a one-out single to third baseman Matt Carpenter. Center fielder Jon Jay followed with a single to right and Carpenter continued home when right fielder Gregory Polanco bobbled the ball for an error.

Reynolds followed with his 13th homer of the season, a drive into the right-field stands.

"It was big hit by Matt then a good piece of baserunning by him and aggressiveness on (third base coach) Jose Oquendo's part to wave him," Matheny said.

Though the Pirates are seemingly consigned to a third straight second-place finish, they insisted the loss was not crushing.

"We've showered off tough losses before," Pirates manager Clint Hurdle said.

Reliever Jonathan Broxton (4-5) pitched a scoreless eighth inning for the win and closer Trevor Rosenthal got through a shaky ninth for his club-record 48th save in 51 opportunities. The record of 47 was set by Lee Smith in 1991 and matched by Jason Isrinhausen in 2004.

Six Cardinals pitches combined on a six-hit shutout -- despite issuing 10 walks -- as the Pirates, who like St. Louis have already clinched a postseason berth, stranded 16 baserunners.

The Pirates left the bases loaded three times and put runners on first and second with none out in the ninth before Rosenthal closed it out.

"We always talk about being a resilient team but it would be hard to be any more resilient than we were in this game," Matheny said. "Our backs were against the wall all night."

Yet the Pirates weren't able to push across a run.

"We've got to move on from this and not worry about guys left on base," Pirates third baseman Josh Harrison said. "We did something right. We were getting on base but baseball's a funny game. You've got to cash in when you get those opportunities and we fell short tonight but it doesn't do anything to deter us from the way we play. We'll continue to put pressure on and tomorrow will be totally different."

Lynn weaved his way through five shutout innings, though he gave up four hits and four walks while striking out six.

Pirates left-hander J.A. Happ allowed only one hit over six scoreless innings and retired the last 11 batters he faced yet wound up not factoring in the decisions. He struck out four and did not walk a batter.

Happ allowed two runs or less in seven of his last eight starts.

Cardinals rookie left fielder Stephen Piscotty was originally diagnosed with a head contusion after being carted off the field on a stretcher in the top of the seventh inning after colliding with center fielder Peter Bourjos.

Bourjos caught a long fly ball to the left-center field gap by Pirates third baseman Josh Harrison. Bourjos' right knee then banged into Piscotty's head.

Piscotty was taken to a local hospital for further evaluation.

"It's hard to see something like that happen but (players) are really good about compartmentalizing things," Matheny said. "You realize there is nothing you can do to help him but keep playing the game. Thankfully, it looks like he's going to be OK."

NOTES: Cardinals C Yadier Molina (partially torn left thumb ligament) will miss the rest of the regular season, and his status for the postseason is in question after being examined by doctors Monday. He will be re-examined Sunday. Molina has been out Sept. 20. ... RHP Adam Wainwright (torn left Achilles' tendon) pitched a simulated game on Monday afternoon and could be activated Wednesday night and available to pitch in relief for the finale of the three-game series. The Cardinals' longtime No. 1 starter has been on the disabled list since April 26. ... Cardinals RHP Michael Wacha (17-6, 3.15 ERA) will face Pirates RHP Charlie Morton (9-8, 4.54) on Tuesday night.