St. Louis ? Trailing by three runs after two innings, the Pittsburgh Pirates were thinking, “Oh no, not again.”

Instead, they kept showing their resiliency against the NL’s best team.

Jason Bay hit a pair of game-tying home runs, and Jose Castillo hit a tiebreaking shot in the 10th inning, leading the Pirates to a 5-4 victory over the St. Louis Cardinals on Sunday.

“I couldn’t be more proud of them today,” manager Lloyd McClendon said. “You talk about big wins in the course of a season for a young team, they don’t get any bigger than this.”

Bay had four RBIs for the Pirates, who earned a split in the four-game series and beat the Cardinals for only the second time in 16 meetings after losing the previous two games by a combined score of 16-1.

“They pretty much had their way with us the last two games,” Bay said. “Early on, it looked like it might have been more of the same, and we’ve been on the other end of that more often than not.”

Bay’s three-run shot tied the game at 3 in the third, and he tied it again with his 15th homer leading off the ninth against Jason Isringhausen, who blew only his second save opportunity in 23 chances. The homer came on an 0-2 hanging curveball.

“Doing this job you’ve got to get lucky every once in a while,” Isringhausen said. “I threw him a bad pitch, and I didn’t get too lucky, and he hit it out, so I tip my hat to him.”

Yadier Molina homered for the third straight game and had three RBIs for the Cardinals, who hit 11 homers in the series. Reggie Sanders also homered, but St. Louis hurt itself by hitting into six double plays, one of them on a bizarre play in the fourth when Molina passed Abraham Nunez on the bases on what looked to be a double off the right-field wall.

“I think everybody knew what was going on but me,” Nunez said. “I noticed (Molina) passed me, and he was pointing, ‘Go to second, go to second,’ but you don’t realize, and it was too late.”