Phelps on SNL

Michael Phelps (center) appears with Lil Wayne and Amy Poehler on 'Saturday Night Live,' where Phelps was the host. Phelps created a stir at Rockefeller Center in New York. (Photo: NBC / September 11, 2008)

It's very late at 30 Rockefeller Center, where it's been dark for hours, the stores long closed. Yet tourists and determined sightseers crowd the entrance, slog into an impossibly long but ever-growing line or just huddle around, camera phones on standby.

A glimpse of Michael Phelps is all they want. With the Olympic champion hosting Saturday Night Live, such glimpses are the hottest of commodities, another Fifth Avenue luxury to covet.

Matt Schwartz and Kasey LaFlam, both 24 and from New York, are among the lucky, with spots toward the front of the line that might allow them to make it into the show. When Schwartz found out Phelps was the headliner, he knew he'd be risking life and limb to take anyone but LaFlam.

"She's completely obsessed," he says.

Obsessed, that is, not with the eight gold medals, not with his speed, butterfly stroke or legendary dolphin kick. For LaFlam, as for so many dreamy-eyed others, it's, well, how Phelps looks in that Speedo.

"Mmm, yeah," she sighs. "Yeah."

Operation Ogle may be fully engaged on Saturday night, but the troop surge has built for days, starting when Phelps began frequenting 30 Rock earlier in the week for rehearsals.

And the seen-it-all city set can't blame the breathlessness entirely on tourists.

It's also the people who work in the building - people who typically aren't prone to bouts of star-struck giddiness since, at the NBC offices, big names are about as common as coffee stations.

While vacationers on the NBC tour press their noses - literally - onto the glass window overlooking SNL's studio, workers from other floors suddenly remember very important errands that require passing by the 8th floor.

"People in the building have been all, 'Ohmygosh it's Michael Phelps!'" says Lauren Roseman, a publicist with the show. "It's pretty funny."

At the rehearsal Friday afternoon, Phelps is hunkered down on what's supposed to be a locker room bench for a skit about a hopelessly bad swim team. "I don't know, coach," he's reading from a cue card a few feet away from him. "I got a bad feeling about this. A Real. Bad. Feeling."

Continuing, Phelps, or team captain "Michael Phillips," tells Will Forte, who's playing the coach, of a premonition in which "I fudged my Speedo."

He imbues the indelicate line with a look of wide-eyed earnestness that he manages to hold for about three seconds before succumbing to the giggles.

The sketch wraps and Phelps is still laughing.

Around him stage crews and sound and lighting experts rush about, hammering sets into place, planning and re-planning shots and endlessly revising lines to throw out the un-funny and make the funny stuff funnier still.

Though he's chosen this high-profile, high-wire act to make his acting debut, Phelps couldn't appear more relaxed. In the tedious lags between sketches, as stagehands all but run, they're so frantic, he's chatting with the cast, stretching his crazily long arms, thumbing his Blackberry.

A crew from 60 Minutes is on the balcony filming footage for a Phelps profile to air later this fall. The reporters crack up at Phelps' Speedo-spoiling line.

Down below the man of the hour is looking anything but, wearing the same purple hooded sweatshirt and flip-flops he sported earlier in the week on The Tonight Show. After weeks on the road, his agent, Peter Carlisle, admits that he and Phelps both have a serious laundry issue.