Selena Gomez opens up about Justin Bieber as she promotes new album in crop top

The subject of her ex-boyfriend Justin Bieber and his headline-grabbing bad behaviour is one that Selena Gomez can be rather touchy about.

But the pop star gave a rare insight into their continuing relationship today as she talked about her former love.

'He and I have such a history together and I'll always care about him and protect him if somebody...,' she said, tapering off.

It came as Selena performed a clutch of tracks from her first studio album Stars Dance on Good Morning America on Friday morning.

All about that stomach! Selena Gomez shows off her toned waistline as she starts the day with a performance on Good Morning America in New York on Friday

Toning it down: While her cropped top revealed her stomach Selena was careful to avoid showing too much flesh by choosing a long-sleeved top and modest leather trousers

The show was billed as a belated birthday bash for the 21-year-old.

And she certainly dressed up for the occasion, revealing her toned stomach in a cropped top.

Aware of her young fan base Selena toned down the daring look by choosing a long-sleeved top and modest leather trousers.

Go Selena: At 21 the former child star is on top of the world

She wore her brown hair loose and curled as the Come And Get It singer talked on the show about her success.

'It's incredible for me, I'm having a great time,' she admitted. 'I just try and be with friends and family and enjoy it now and then.'

But Selena says she still has much to achieve.

'I don't feel like I'm settled yet,' she said. 'I still feel like I've got to continue to strive. If I'm not working I feel bored and then I feel crazy.'

She's got the moves: At one stage the young star jumped into a chair as she sang

The singer-actress, who had her breakthrough on Disney Channel's Wizards of Waverly Place at age 15, doesn't have much time for much other than her career at the moment.

After her GMA performance she headed straight to the next show with a performance on Kelly And Michael.

With her debut studio album Stars Dance currently at number one in the U.S. charts she is at a critical stage in her budding pop career.

'Genuinely, the whole record is me being a woman and wanting to explore that and being comfortable in my skin and my body, and exuding confidence,' she told AP.

Got the moves: Selena and her back up dancers are in sync for the cameras

'People speculate or think what they want to think, but it's been really fun for me to kind of explore what I want to explore.'

Spring Breakers star Selena will kick off a 56-city world tour - where she'll play venues like the Staples Center in Los Angeles and Barclays Center in Brooklyn, N.Y. - in Vancouver, British Columbia, on August 14.

It wraps November 27 in St. Louis.

Yum! Selena was presented with a beautiful floral cake to celebrate her recent 21st birthday