Justin Bieber performed at London's O2 Arena, and his fate tonight was far worse than being booed for tardiness -- the 'Beauty and a Beat' singer was hospitalized immediately following the concert.

Bieber reportedly felt lightheaded and queasy throughout the show, and with four songs left, he stumbled backstage and collapsed.

The Canadian phenom was moved to a private room where emergency personnel administered oxygen to the singer, who was advised to go to the hospital immediately. However, possibly facing the guilt and backlash that ensued with a recent late-starting O2 Arena show, Bieber was determined to finish the concert for his beloved Beliebers.

While he was backstage being treated, his everpresent manager, Scooter Braun, went onstage to explain to Bieber's fans what had gone down and where he went.

"Justin's got very light breath," Braun told the shrieking crowd. "The whole show he’s been complaining, He’s backstage with the EMTs and the doctor."

Bieber returned shortly thereafter to finish out the show, receiving an appreciative ovation unseen or heard since the Beatles.

"The fans were so supportive and cheering him on and chanting his name," concert attendee Lauren Odell told E! News. "He came back on and finished with 'Believe,' 'Boyfriend' and 'Baby,' but struggled with energy."

He's reportedly feeling better, but will remain in the hospital for treatment until he's given the all-clear to go.