Coldplay, Conor Maynard, Cover Drive, Ed Sheeran, Example, Flo Rida, Jessie J, Justin Bieber, Katy Perry, Kelly Clarkson, Lawson, Pitbull, Rita Ora, Usher, The Wanted PLUS surprise guests! See the amazing high definition pictures of the Summertime Ball 2012's line-up.
Justin Bieber Hints At Special Guest During Summertime Ball 2012 Performance
The 'Boyfriend' star says he's also looking forward to catching up with mentor Usher at Wembley Stadium.
Justin Bieber has hinted that a special guest may join him during his appearance at the Summertime Ball in London tonight (9th June).
Fans of the 'Boyfriend' star are currently assembling outside Wembley Stadium – more than six hours before the show is due to begin.
Justin took to Twitter this morning to say how excited he was about performing at the event, which will also see his long-time friends Usher perform.
"Me and big bro @usherraymondiv gonna kill it 2nite at Summertime Ball here in London," he wrote.
The singer then surprised his followers by adding: "Got a special guest with me too."
PHOTOS: Justin Bieber's Best Moments In Pictures.
Speculation is now growing at Wembley as to who may join the 18-year-old superstar tonight.
Justin Bieber performing with Usher at the Summertime Ball two years ago:
Today's Summertime Ball will also feature performances from the likes of Coldplay, Katy Perry, Jessie J, Ed Sheeran and Example.
Find out who joined Justin Bieber at the Summertime Ball
The Wanted and Lawson will also perform later.
Capital FM is coming live from the Summertime Ball at London's Wembley Stadium on 9th June.
Keep your eye on the ball by heading to our Summertime Ball area for all the latest news, photo galleries and interviews from this year's event.
Capital gets ready for Justin's appearance at the Summertime Ball by seeing how many of the 'Boyfriend' star's songs you can guess in our new quiz.
To celebrate the fact our favourite teen sensation is turning 18 we thought it would be a great chance to look back at some of the 'Baby' singer's best moments over the years.
Latest Justin Bieber
The 'Beauty And A Beat' star is seen receiving a kiss on the cheek from his ex-girlfriend at the awards show.
The 'Boyfriend' singer missed his headline to collect the pet after it was confiscated in Germany.
Justin Bieber was booed by fans for arriving on stage two hours late for the first of four gigs at London's O2 Arena. Check out pictures of what happened when he finally took to the stage.
Watch the Black Eyed Peas singer's new video featuring the 'Boyfriend' star now on Capital.