ELLE cover star Rihanna celebrated her 25th birthday with a jet-ski lesson in Hawaii yesterday.

The delighted singer looked to be having a ball – even if she was a little unsteady on her skis.

She later tweeted a picture of herself with Chris Brown in the back of a car, with the caption: ‘Pour it up pour it up! #birthdaybehaviour’.

The star missed last night’s Brit Awards for the festivities. She had been nominated for International Female Solo Artist.

It’s little wonder she needed a break, though – it’s been a busy few weeks for RiRi, what with launching her first fashion collection with River Island and announcing a ground-breaking deal with make-up giant MAC. Plus, of course, there’s her starring role in ELLE’s April issue – watch our exclusive video of her introducing it now – which hits newsstands 6 March...