St. Louis: The Rally Squirrel became the St. Louis Cardinals’ unofficial mascot during their 2011 World Series championship run.

On Wednesday night, the Rally Cat was born.

Yadier Molina blasted a grand slam into the left field seats one pitch after a cat ran onto and across the field in the sixth inning, helping the Cardinals rally to beat the Kansas City Royals 8-5.

“It’s amazing,” Molina said. “You see some animal coming through a field. You expect people to jump on the field but you never expect an animal. It was fun.”

The win was the third straight for the Cardinals against the Royals and the fifth straight overall.

Molina’s big blast — after a little help from a friendly feline — made the difference on a night the teams combined for 13 runs and 26 hits.

“I’m not a cat person but I sure liked that one,” Cardinals manager Mike Matheny said.

The Cardinals loaded the bases off Royals relievers Brandon Maurer and Peter Moylan. Molina was at the plate, with two outs, when the cat came onto the field and ran toward the center field wall.

“I heard the crowd erupt and I thought there must have been something on the scoreboard,” Moylan said. “I turned around and there’s a kitten running around, which is the first time that’s happened to me.”

On the next pitch, Molina drilled his 14th homer of the season into the left field seats for his fifth career slam.

“I left a pitch over the middle of the plate and I paid for it,” Moylan said.

Melky Cabrera hit his 15th home run, a two-run shot that had given the Royals a 5-4 lead in the fifth.

Whit Merrifield had four for the Royals, who opened the game with four straight hits off Mike Leake and took a 2-0 lead on an RBI double from Lorenzo Cain and RBI single by Cabrera.

Merrifield made it 3-0 when he scored on Molina’s throwing error in the second.

The Cardinals scored twice in the second, on an RBI sacrifice bunt from Leake and an RBI single from Matt Carpenter, and then tied the game on Jedd Gyorko’s RBI single in the third.

Jose Martinez gave St. Louis a 4-3 lead in the fourth inning with his ninth homer.

Leake, the Cardinals’ starter, allowed five runs on 11 hits in five innings. Royals starter Trevor Cahill lasted just 2 1/3 innings, allowing three runs on four hits and walking five.

Matt Bowman (3-4) earned the win. Maurer (1-5) took the loss.

Trevor Rosenthal closed out the ninth inning for his ninth save.