“American Pie” cutie Tara Reid spent hours knocking back drinks and collapsed at a Las Vegas nightclub!

The rail-thin actress stunned onlookers who witnessed the scene at Ghost Bar, a chic hotspot located on the 55th floor of the Palms Casino Resort.

Tara, 27, was a presenter at the 2002 Billboard Music Awards in Vegas on December 9, and was invited to a post-awards party at Ghost Bar by Limp Bizkit rocker Fred Durst.

She arrived with JC Chasez of *NSYNC and a group of security guards at midnight and “immediately began drinking in the VIP section,” a source at the club disclosed.

An eyewitness said Tara and Chasez “were kissing and cuddling the entire night.

“They were all over each other from the moment they arrived. You couldn’t have slipped a credit card between them!”

After two hours of drinking with Durst, Chasez and the rock band Puddle of Mudd, Tara began to wobble on her feet and asked for an escort to the bathroom, said the eyewitnesses.

“She was having trouble getting herself to the bathroom and her bodyguard was trying to get people out of the way.

“Tara was loudly demanding that the women in line for the bathroom get out of her way. She was throwing a fit and shoving people. Before she made it to the bathroom she just collapsed in the hallway between the women’s room and the elevator!

“As soon as she went down it was pandemonium. The club security was trying to help her and her personal bodyguards were pushing and shoving people away and trying to make room for her.”

Another source revealed: “One bodyguard was trying to help her to her feet and was angrily warning partygoers not to take any pictures. He threatened to ‘break any cameras’ if anyone took pictures.”

Said the eyewitness: “As soon as Tara got to her feet she began crying hysterically. Her mascara was streaming down her cheeks. Her face was red and her hair was hanging in her face. She was a mess.

“Security cleared the bathroom and Tara went in with an entourage and they cleaned her up. She was in the bathroom for about 20 minutes and when she came out she seemed to have regained some of her composure, but everyone was staring at her and whispering.

“Then she went right back into the VIP room and stayed at the club for a few more hours!”