Canadian singer Justin Bieber has canceled one of two concerts scheduled for this week in Portugal, the venue in Lisbon said on its website on Monday.
It was not immediately clear whether the cancellation was linked to his collapse on-stage in London last week which forced the teen sensation to take a 20-minute break to receive oxygen and then to stay overnight in hospital.
"Due to unforeseen circumstances, Justin Bieber was forced to cancel the second performance in Portugal, March 12," a statement said on the website of the Pavilhao Atlantico.
"The Canadian singer is eager to play for the Portuguese fans on March 11," it added. Ticket holders for the canceled gig were entitled to a refund if they claimed it within a month.
His U.S.-based representatives were not immediately available for comment.
Bieber described his visit to London as a "rough week."
As well as the collapse, the 19-year-old was caught on film in an expletive-filled altercation with a photographer, showed up nearly two hours late for a show leading to widespread anger and was labeled a "pop brat" by a leading tabloid.
Discovered on YouTube in 2008, Bieber has built an online following of tens of millions of fans and is one of the pop world's biggest stars. In February, he became the youngest artist to land five chart-topping albums in the key U.S. market.