If there’s any hope of the Pittsburgh Pirates getting things back on track this year following a putrid start to the season, it’ll have to begin with a single win.

Monday night in St. Louis offered the latest opportunity to initiate some sort of reversal of fortunes.

Entering first pitch against the Cardinals at Busch Stadium winless in May and losers of four straight, the Pirates saw a one-run lead evaporate in the sixth inning before St. Louis won, 6-3.

The Cardinals plated four runs in the sixth, all off reliever Chase Shugart.

Shugart (1-2, 3.68 ERA) had allowed only two runs in 14⅔ prior innings this season. On Monday, he was roughed up for five hits and four runs, including a go-ahead two-run homer by Willson Contreras.

“It happened with a guy (Shugart) that has pitched really well and he just didn’t have it tonight,” manager Derek Shelton said on the SportsNet Pittsburgh postgame show. “Sometimes that happens.”

Carmen Mlodzinski (6.16 ERA), making his seventh start of the season, lasted 4⅔ innings, allowing two runs, both on solo homers, with four hits and two strikeouts.

The Pirates (12-24) managed only seven hits in the defeat and were 2 of 9 with runners in scoring position.

After Oneil Cruz led off the game and hustled to get aboard via an infield single, Bryan Reynolds gave the Pirates a 2-0 lead in the first inning by hitting his fifth homer of the year to right field off St. Louis starter Miles Mikolas.

The Cardinals (17-19) tied the score in the third with a pair of solo shots off Mlodzinski.

Jose Barrero made it 2-1, lifting a 3-2 fastball to left field. Two batters later, Alec Burleson connected on the first pitch Mlodzinski offered, depositing it over the right-center field wall.

The Pirates quickly retook the lead, 3-2, in the fourth, courtesy of an Adam Frazier RBI single into shallow center field that plated Joey Bart from second.

Bart led off with a walk and moved up a base when Enmanuel Valdez singled.

Mikolas then walked Tommy Pham to load the bases, but Jared Triolo grounded into an inning-ending 6-4-3 double play, spoiling a chance at more runs.

The double play was the Pirates’ 36th of the season, which leads MLB.

In the fifth, Shelton opted to stick with Mlodzinski, who has struggled heavily this season when navigating through opposing lineups the second time.

While Mlodzinski managed to do so without issue, retiring St. Louis’ No. 8 and 9 batters, Victor Scott and Barrero, to record two outs in the frame, Shelton ended Mlodzinski’s evening in favor of Ryan Borucki.

“I think he did a good job with what we asked him,” Shelton said of Mlodzinski. “At times, there’s going to be times where we ask certain things of people and right now, (starting) is what we’re asking him. He gave us a chance to win the ballgame. That’s all you can ask for.”

Borucki walked Lars Nootbaar but got Burleson to softly line out, ending the inning and preserving the lead.

With one out in the sixth, Shugart took over on the hill for the Pirates and walked Nolan Arenado.

Shugart, one of the Pirates’ most dependable relievers so far this season, then was taken deep by Contreras before allowing three straight singles to Nolan Gorman, Pedro Pages and Scott, loading the bases.

From there, Shugart’s worst appearance of the season continued as Barrero ripped a ground-rule double down the left-field line to make it 6-3 St. Louis.

Shelton soon replaced Shugart with Caleb Ferguson — with runners still on second and third.

Ferguson got Nootbaar to fly out to center field, and Cruz made a spectacular throw to home plate, nabbing Scott for an inning-ending double play.

Joey Wentz delivered two scoreless frames in the loss, pitching the seventh and eighth, allowing two hits and a walk and striking out three.

With two outs in the ninth, Reynolds came to bat with two men on, representing the tying run.

On the first pitch he saw from Ryan Helsley, he hooked a shot foul deep down the right-field line, narrowly missing a home run before ultimately striking out looking to end the game.

“We had a couple of opportunities, too, at the bottom of the order that we didn’t capitalize on,” Shelton said of the Pirates’ eight baserunners stranded. “We have to capitalize on those opportunities to win.”