Under-fire Canadian pop star Justin Bieber halted his London show for 20 minutes after complaining of being "light of breath".
Bieber, who angered fans after turning up nearly two hours late for Monday's show at the O2 Arena, returned to the stage to complete his set before being taken to hospital.
In a video posted by a fan on YouTube, Bieber's manager Scooter Braun tells the crowd: "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."
Celebrity website TMZ reported that a source close to the singer said he "felt woozy" during the show.
His representative told entertainment channel E! News that emergency personnel gave him oxygen.
"He insisted on finishing the show," she added, as he was being taken to hospital.
Bieber blamed Monday's PR disaster on technical difficulties and will hope his stoic efforts to complete Thursday's show will placate his legion of teen-fans.
He was performing the third of four shows at the arena as part of his "Believe" world tour.