STARS COME OUT FOR RIHANNA'S ALBUM RELEASE PARTY IN NEW YORK!

Rihanna certainly knows how to make a comeback.
The songbird's first big NYC bash in honor of her album "Rated R," which was released Friday, was anything but ordinary.

Although the 21-year-old didn't show up at the Tuesday-night fete (which began at 10) until 1 a.m., several of her guests, including Jay-Z, P. Diddy and Fabolous, arrived, er, promptly at midnight at the Juliet Supperclub.

Just about the only person who was on time was a little girl, clad in pajamas and escorted by her dad, who was waiting for RiRi's arrival. Partygoers report that as the girl jumped up to take a picture of Jay, she accidentally knocked Diddy in the head — sending the music mogul flailing backward.

"For a second he looked totally out of it, like he didn't know what hit him," a spy outside the fete said. "Then he and Jay couldn't stop laughing about it, but she smacked him pretty hard."

Luckily, he recovered within moments, just in time to file into the bash with the likes of Tyson Beckford, Selita Ebanks and Rick Ross.

When Rihanna did grace the Chelsea hot spot with her presence, she brought along a five-person security team and a 20-person entourage — which quickly escorted her through Todd English's eatery and into the kitchen.

There, Ri made a quick costume change (her fifth of the day) and switched from gold sparkles to red sheath (and, naturally, sunglasses) while several dishwashers did their best to look on.

"The guys in the kitchen were going nuts," one lucky party guest says, adding that despite the security's best efforts to keep her covered, a little back was shown.

"On her way out to the party she stopped to say hi to some of the kitchen workers," the source says, "and they all went absolutely berserk."

Once finally inside her fete, Ri was greeted with a cake (from Buddy Valastro of TLC's "Cake Boss"), who was also at the party.

"Rihanna went straight into the VIP section and looked like she was having a blast," our spy says, noting that she was hanging out with a lot of girlfriends and that there was no particular man-of-the-moment in sight.

Adds the source: "She was dancing to a lot of her own songs and didn't leave until after 3 a.m."