Justin Bieber left the stage mid-song during his O2 concert after complaining of being "light of breath", his manager has said.
The teen sensation was performing in front of thousands of fans on the third night of the London leg of his world-wide tour when he fell ill.
His manager Scooter Braun said he was seen by a doctor backstage at the venue who told him not to return to the stage. However, fans reported that he did make it back to the spotlight to finish his Believe show.
In a video posted by a fan on YouTube, Justin's manager Scooter tells the audience: "Justin got very light of breath, the whole show he's been complaining. He's backstage with the EMTs (emergency medical team) and the doctor.
"They're telling him they want him to go and see somebody and find out what's going on with his lungs, he's just told me that in five minutes, if it's OK with you guys, he's going to come out and finish the show."
The manager had previously tweeted his joy that Justin started the show 10 minutes early.
It comes after the singer was heavily criticised by fans and parents of young children for starting his concert late on Monday night. Many were reduced to tears when forced to leave the venue just minutes into his performance, which started shortly after 10pm, in order to catch trains homes. The star later apologised and blamed the delay on technical difficulties.
Justin later published a picture of himself in a hospital bed after being checked by doctors for breathing problems. The singer, who uploaded the pictures to his Instagram account, also thanked fans for supporting him while he "figures out" what happened. He said: "Getting better. thanks for everyone pulling me thru tonight. best fans in the world. figuring out what happened. thanks for the love."