[starttext]
By DAILY MAIL REPORTER
Celebration: Rihanna takes over the DJ booth as she performs with a glass of champagne in hand, watched on by Jay-Z, at a star-studded party at The Cosmopolitan hotel in Las Vegas on New Year's EveThe champagne was in full flow as Jay-Z hosted a New Year party in Las Vegas which was bubbling with some of the biggest stars in the entertainment industry.
Joining the rapper was his wife Beyonce, along with Rihanna, Gwyneth Paltrow, her husband Chris Martin, Kanye West, Jennifer Lopez and Florence Welch.
The stars were out in force for the grand opening of The Cosmopolitan, a $3.9 billion hotel on the famous Strip.
Following a gig, which included performances from Beyonce, Jay-Z, and Coldplay's Chris, the celebs partied until the earlier hours at the Marquee Nightclub in the hotel.
Beyonce, 29, duetted with her 41-year-old husband to perform Forever Young and also teamed up with Chris to sing her hit Halo, wearing a stunning low-cut dress.
John Mayer also made a surprise appearance, playing guitar with Jay-Z on his song 99 Problems.
Having a ball: Rihanna looked eye-catching in a red dress, which matched her hair, seen her dancing with Jay-Z
Getting the crowd going: The singer performed her new hit track What's My NameKanye West took over the DJ boot at 2.30am and was joined by Jay-Z as they sang Runaway followed by Monster.
And not wanting to miss out, Rihanna performed her new track What's My Name, looking glamorous in a red dress which matched her hair.
Other guests included Cameron Diaz and A-Rod, who jetted in fresh from their holiday in Mexico.
In full flow: The VIPs quaffed Armand de Brignac champagne, which cost a cool $300 a bottle
Fancy a top up: Rihanna gets a refill at the event, which saw a host of stars perform The VIPs quaffed Armand de Brignac champagne, which cost a cool $300 a bottle.
The vintage drink, sometimes referred to as Ace of Spades in song lyrics, is a favourite among the hip hop crew and made an appearance in Jay-Z's music video Show Me What You Got.
'All the problems you were going through have been kicked out the door,' Jay-Z told the crowd before collaborating with West on Homecoming, which also featured Chris Martin.
Check out the dress: Beyonce performed her song Halo, wearing a low-cut number, and was accompanied by Coldplay's Chris Martin on the piano
Applause: After the performance, party host Jay-Z came on stage and spoke to Chris before addressing the crowd of party-goers 
Curvaceous: Singer and actress Jennifer Lopez and Gwyneth Paltrow were also among the guestsDiaz spent some time chatting with J-Lo and the singer's husband Marc Anthony as Ellen Pompeo and Blake Lively mingled nearby.
Before the concert Pompeo said she doesn't make New Year's resolutions, but said her goal for the year ahead was to be 'happy every day'.
'I have a great job, a great husband, a great baby. I have a lot to be thankful for all the time,' the Grey's Anatomy star told People.com.
DJ Eric Morrillo was also on hand, spinning some tunes on the decks as the revellers partied into the early hours.
Legs on show: Grey's Anatomy star Ellen Pompeo, left, and singer Florence Welch, who donned a pair of eye-catching hot pants
Trio of fun: Jay-Z collaborated with Kanye West on his hit Homecoming and Chris also joined in
Cool gang: Floyd Mayweather, 50 Cent, Jay-Z strike a pose, dressed in all their finery
Dancing until the early hours: Rihanna, Jay-Z ad Kanye get into the party spiritsource: dailymail [endtext]
