PITTSBURGH -- St. Louis Cardinals catcher Yadier Molina says a loss is a loss, no matter how traumatic it is.

The looks on the faces of the surging Pittsburgh Pirates -- and the suddenly altered look of the National League Central standings -- say something else.

Gregory Polanco lined a game-winning single to right field to cap off Pittsburgh's three-run rally in the 10th inning against All-Star closer Trevor Rosenthal, and the Pirates won their second dramatic game against the Cardinals in as many nights, 6-5 on Sunday.

"Yeah, it was kind of tough. Yeah, it was tough," Molina said after the Cardinals couldn't hold an extra-inning lead for the second time in 24 hours.

St. Louis left fielder Randal Grichuk's two-run double broke a tie in the 10th inning and put the sliding Cardinals in position to split the four-game series, but the Pirates scored three runs with two outs against Rosenthal -- who converted all but one of his previous 27 save opportunities.

Third baseman Jung Ho Kang followed left fielder Starling Marte's single with an RBI single ahead of catcher Francisco Cervelli's tying single to right as the last five Pirates batters reached base. Polanco then won it with a line shot to right, his first career walk-off hit. Polanco had three hits and two RBIs.

The Pirates trimmed the Cardinals' NL Central lead to 2 1/2 games only two weeks after they were down by nine games on June 28. They also followed up their dramatic, comeback-filled 6-5, 14-inning win Saturday on center fielder Andrew McCutchen's walk-off, two-run homer with another improbable rally.

"The last two nights were amazing," Pirates shortstop Jordy Mercer said.

Pittsburgh (53-35) won eight of its past nine and 11 of its past 13. The Cardinals are a major-league-best 56-33 but have dropped three in a row and five of seven.

Still, Molina said the two losses -- no matter how gut-wrenching they were -- are merely two defeats in the standings.

"It's a loss, no matter how it is," he said.

Molina's RBI grounder tied it in the eighth against left-hander Tony Watson, and Grichuk's two-run double appeared to put the Cardinals in position to win with Rosenthal (1-2) coming on.

"When you get sucker-punched in the late innings, then you're able to grind it out and give yourself an opportunity to win, that's a sign of a resilient team, and that's what we have," Pirates second baseman Neil Walker said.

The Pirates go into the break with a major-league-best 40-19 record since May 9.

"We do a really good job of battling," Walker said. "Games like tonight and last night are a reason why this team's pretty special."

Right-hander Arquimedes Caminero (1-1) got his first major league win despite allowing two runs in the 10th.

The Cardinals, 5-0 previously in Sunday night games, took a 1-0 lead against Pirates left-hander Francisco Liriano in the second on three singles, a walk and a double-play grounder. However, in the bottom of the second, the back part of the Pirates' batting order produced a two-run rally against Cardinals rookie left-hander Tim Cooney, making his fourth career start.

Cervelli hit a one-out triple to center -- only his third triple in the past five seasons. After first baseman Sean Rodriguez was retired on a short fly to right, Polanco was intentionally walked. Liriano, batting only .057, crossed up the Cardinals with a long, two-run single to the right field wall. Liriano previously had three RBIs in his 10-season career.

National League All-Star shortstop Jhonny Peralta tied the score at 2 in the third with his 13th homer, a drive into the left-center seats on a 3-2 count.

The bottom end of the Pirates' order came through again in the fourth. Rodriguez doubled to right with one out, and Polanco -- batting only .114 with two RBIs in 44 at-bats this season against left-handers -- lashed an RBI single to right, giving Pittsburgh a 3-2 lead.

Now comes the season's second half -- and nine more games between the Cardinals and Pirates, six in St. Louis, in what might be the majors' best head-to-head race. The Cardinals and Pirates own the majors' two best records.

"We know they're not going to go anywhere. We're not going to go anywhere," Molina said. "We just have to play better."

NOTES: St. Louis LF Randal Grichuk's hit in the 10th would have been a triple, but 1B Mark Reynolds was thrown out at the plate trying to score from first. ... RHPs Lance Lynn and John Lackey will start the first two games of the Cardinals' series against the New York Mets next weekend. Manager Mike Matheny might hold back All-Star RHPs Carlos Martinez and Michael Wacha -- both on pace to throw 200 innings -- until the Chicago White Sox series that begins July 21. ... Coming off the 14-inning game in which they used six relievers, the Pirates recalled RHP Wilfredo Boscan from Triple-A Indianapolis for the second time this season. He didn't appear in a game while with them from May 16-18. UT Steve Lombardozzi was optioned to Triple-A. ... Cardinals 2B Kolten Wong was back in the lineup after being lifted due to a tight hamstring in the 11th inning Saturday night. ... Pirates RHP A.J. Burnett, headed to his first All-Star Game at age 38, plans to wear black-and-gold cleats with a Batman-like theme Tuesday night in Cincinnati.