Harry Styles celebrated his birthday with ex-girlfriends Cara Delevingne and Kendall Jenner.

The One Direction heartthrob - who turns 21 today (01.02.15) - welcomed in the milestone with pals at a star-studded party in Los Angeles on Saturday evening (31.01.15), with 'Rolling in the Deep' hitmaker Adele and former footballer David Beckham among other A-list guests in attendance.

The 'Steal My Girl' singer's reported girlfriend Nadine Leopold - who celebrated her 21st birthday just three weeks ago - was also spotted at the occasion, following reports the pair ''can't stand being apart.''

A source revealed to The Sun newspaper: ''Everyone's teasing him, saying he's in love, and he's not denying it. It's the real deal. He's never felt this way about anyone before.

''Harry has spent virtually all his free time in Los Angeles with Nadine. They're infatuated with each other and can't stand being apart. There's nobody else he'd rather be with on his birthday.''

Although bandmates Liam Payne and Louis Tomlinson partied with the group's youngest member, Niall Horan was in Melbourne watching Andy Murray compete in the Australian Open Men's Final and 22-year-old Zayn Malik was no-where to be seen.

James Corden and his wife Julia, Jennifer Lawrence and Chris Martin, Rita Ora, Kelly Osbourne, Cindy Crawford, Kimberly Stewart, Zach Braff and Alexa Chung also attended the bash, where guests were treated to karaoke and cupcakes.