Jeff Probst (search), the host of "Survivor: All-Stars," (search) says he realizes now that he goofed on last week's all-important immunity challenge - and chose the wrong "winner."

"I blew another one," Probst told The New York Post yesterday. "Part of the rules and the contract [the contestants] sign is that during the challenges I'm the sole arbiter and final call.

"They're often judgment calls," Probst said. "This is one I just blew."

On last week's immunity challenge, members of the Mogo Mogo and Chapera tribes had to run across a long balance beam to retrieve their tribe-colored flags, tangling with each other to get to the flags.

Since this is "Survivor," where everything is more difficult, the balance beam was perched over a pool of water. The first person from either team to fall off and hit the water was the loser.

In the end, it boiled down to the Chapera tribe's Rob Mariano facing off against Mogo Mogo tribe's Colby Donaldson.

Rob and Colby grappled for their flags and tumbled into the water together in a big blur. With the naked eye, it appeared that Colby hit the water first.

Probst, perched on a judging seat several feet away, ruled in Rob's favor.

But a frame-by-frame analysis reveals that Rob's foot actually hit the water a split second before Colby's arm.

"I remember Rob looking up at me on that one [in disbelief]," Probst said. "I hate water challenges like that because when you're watching it, and a guy's body hits the water and makes a huge splash with the other guy right behind him, you can't see it without six angles," Probst said.

"I might be influenced if they didn't moan about every single call and look at me like I blew it every time.

"The next time I play poker with [Colby] Donaldson he needs to be reminded to ease up a bit," Probst joked.

But maybe, despite the gaffe, Probst actually did some fans of "Survivor" a huge favor.

With Chapera winning the immunity challenge, that meant that big, naked Richard Hatch from the Mogo Mogo tribe was voted off the island - and none-too-soon for some viewers tired of seeing him parade around in the buff.

This "All-Stars" edition, which took place in Panama, features stars from past "Survivor" shows and has averaged a robust 22.7 million viewers for CBS.

The show's live finale, followed by a live reunion show, will air Sunday, May 9 from Madison Square Garden (search).