Following an emotional week for Justin Bieber, including a paparazzi confrontation in London, the pop sensation canceled one of his upcoming Believe tour stops in Lisbon, Portugal.

Bieber's European leg of the tour had some down moments, such as the singer arriving two hours late to a concert on March 4, and now Bieber is disappointing some Portuguese fans by cancelling his Tuesday night concert.

"Due to unforeseen circumstances, Justin Bieber was forced to cancel the second operation, in Portugal, on 12 March," a representative confirmed to E! News. "The Canadian singer is eager to play for the Portuguese fans on 11 March."

The message also instructed fans who purchased tickets for the concert on how to get their money back: "Holders of tickets valid for March 12 should contact the respective place of purchase to receive a refund within 30 days of the date of the scheduled concert, which ends April 11."

News of the cancellation follows Bieber's onstage health scare in London last week when the singer nearly collapsed on stage and walked backstage to receive "oxygen and treatment backstage."

"When he started 'Beauty and a Beat' you could see he was struggling," said Prithvi Pandya, who was near the front of the crowd. "He took lots of drinks of water, that seemed unusual, and he was really sweaty, sweating a helluva lot."

Bieber was rushed to a nearby hospital and even tweeted a photo to update his fans on his condition. He posted: "Getting better. thanks for everyone pulling me thru tonight. best fans in the world. figuring out what happened. thanks for the love."

His manager Scooter Braun said Bieber experienced trouble breathing throughout his London show but Bieber appears to be doing much better since then.

"Slept good last night," he tweeted March 10. "Hanging with the boys today."

Bieber is still scheduled to go to at least six other European countries in the coming weeks.