An unexpected slider led to an embarrassing episode for the Yankees last night, in which Kyle Farnsworth and Jorge Posada ultimately contradicted their manager.

Posada was crossed up by a Farnsworth breaking ball in the ninth inning, and the furious righty reliever turned his back to his batterymate and walked away when Posada visited the mound.

Posada, who also became livid, stalked back behind the plate as pitching coach Ron Guidry tried to act as a mediator. After a disheartening 5-2 loss to Atlanta in which Farnsworth buried the Bombers by allowing two runs, Joe Torre openly admitted the two teammates had a disagreement.

Neither player would cop to it, however.

“That’s why I sent Gator out there,” Torre said. “I said, ‘I think this may be a little heated out there. You better go out.’ “So when Gator went out, Jorgie went behind the plate.” Torre seemed slightly bemused and played off the emotions of the incident, saying, “That’s the nature of what we do.” But Posada and Farnsworth couldn’t even agree on whether the Yankees catcher was crossed up. The reliever said yes, while Posada said no.

What happened?

“I just missed the ball,” Posada said. “That’s it.” You weren’t crossed up?

“I just missed it,” Posada said.

Asked if he was trying to say something to Farnsworth when he walked away, Posada said, “No.” Farnsworth was similarly disingenuous.

He said Torre’s description of the events was “not accurate.” Is he OK with Posada?

“Yeah, there’s nothing going on,” Farnsworth said. “Whoever said that … there’s nothing going on.” It just looked like …

“There’s nothing going on,” Farnsworth said brusquely.

Farnsworth (2-4, 4.98), shaky in his last three appearances, seemed more riled up after the game. He allowed three hits in two-thirds of an inning, cementing the loss. Earlier in the frame, he had thrown a wild pitch that should’ve been ruled a passed ball.

When asked if he was trying to blow off steam by walking away from the mound (and Posada), Farnsworth allowed that he was “just trying to calm down.” Farnsworth and Posada form an explosive battery. The reliever has quickly become known as an intense competitor with a superhuman pregame workout regimen, while Posada has openly been called hot-tempered by Torre and other longtime Yankees.

Torre thought part of it was frustration over the outcome.

“It wasn’t a good game,” he said.

“The first six innings, it was one of those old-fashioned battles.

“It got ugly.”