George Michael is in a Vienna hospital battling pneumonia.
The 48-year-old singer canceled shows as a result.
The former Wham! front man released the news on his website Wednesday.
"With great regret, George Michael has been forced to postpone his Nov. 26 and 27 shows in Cardiff, Wales, due to his ongoing illness,” said his publicist Connie Filippello in the statement.
"George was recently forced to postpone tour dates in Vienna and Strasbourg under doctor's orders after being diagnosed with pneumonia. He is currently receiving treatment,” the statement explained.
Michael canceled his planned Vienna concert on Monday two hours before it was due to start.
According to Reuters, the British singer “called off a planned gig in Vienna on Monday and another in Strasbourg on Wednesday, and now his Cardiff dates have been put on hold.”
Michael has sold over 100 million records worldwide. His 1987 debut solo album, Faith, sold over 25 million copies worldwide and made several records and achievements in the United States.
His personal life has had its up and downs. He was arrested in 2006 and 2008 for illegal possession of drugs and had a very high profile arrest in 1998 when he was arrested for “engaging in a lewd act” in a public toilet park in Beverly Hills.
In a 2007 interview, Michael admitted that he hid the fact that he was gay because of worries over what effect it might have on his mother.
Michael, whose chart-topping hits as a solo artist include "Faith" and "Careless Whisper," also announced that an earlier cancellation, an Oct. 26 concert at London's Royal Albert Hall, would be rescheduled for May 2, 2012, according to Reuters.
It looks like fans of George Michael will have to wait until the artist fully recovers before they get to see him perform his greatest hits.