Hayden Panettiere and Wladimir Klitschko are totally dating. She just doesn't want people know it yet. She even books extra hotel rooms for that reason, it turns out.

So people wouldn't suspect she was sharing a room with her new boxing-champ boyfriend, the diminutive star had aides book her a room at another hotel.

They did so, and it sat empty - if you know what we mean! We mean Hayden's dating Wladimir Klitschko, and they shacked up in the same room. ALL NIGHT.

"It was clear she was with Wladimir, and they were at the Setai together," a source told the N.Y. Post. "But she insisted on booking a room at a separate hotel."

"Then she could pretend she was staying elsewhere. The room was never used."

Too bad many Hayden Panettiere pictures were taken featuring the bikini-clad star cozying up to the fighter. Talk about getting caught red (hot!) handed:

Hayden Panettiere takes in the beautiful view by the hotel pool. It's hard to blame her. We're sure Wladimir Klitschko is a fan as well. [Photo: PacificCoastNewsOnline.com]

Hayden, who was seen poolside with the Ukrainian boxing champ, who towers over her 5'1" frame at 6'6", has a history of pretending she's unattached.

She repeatedly claimed she was "just friends" with Heroes co-star Milo Ventimiglia. Another guy she said was just a friend? Entourage's Kevin Connolly.

Wladimir sure looks friendly with her in that picture above. Forget his many heavyweight titles - the guy has officially earned the title of Lucky Stiff!