Paris Hilton celebrated her 27th birthday with four parties on Saturday.

The hotel heiress - whose birthday isn't until this Sunday - kicked off her mammoth session with tequila shots at her friend's Hollywood Hills home.

Paris and her entourage, which included Britney Spears' cousin Alli Simms, then moved onto to Area nightclub, where Paris was serenaded by actress Angelica Bridges' version of 80s hit 'Nasty Girl'.

'The Simple Life' star then headed to hip nightspot Villa, where she was joined by Leonardo DiCaprio, John Legend and Jamie Tisch.

A source said: "It was really hot."

The party later moved to a late-night 'Austin Powers'-themed bash in Beverly Hills, where they stayed until 5am.

An onlooker said: "She threw back more and more shots."

Paris' one-time friend Lindsay Lohan missed the night's event, preferring to party at Hollywood nightclub Goa.