Sir Elton John was admitted to hospital with a "serious respiratory infection".
The pop icon was rushed to the Cedars-Sinai Hospital in Los Angeles in the early hours of yesterday morning (23 May) and was told by doctors that he needs "complete rest and antibiotic treatment to prevent damage".
John has also been told by doctors that he cannot perform for seven days, meaning that four of his Million Dollar Piano concerts in Las Vegas' Caesars Palace will have to be cancelled.
John told TMZ.com: "It feels strange not to be able to perform these Million Dollar Piano concerts at the Colosseum.
"I love performing the show and I will be thrilled when we return to the Colosseum in October to complete the 11 concerts.
"All I can say to the fans is 'Sorry I can't be with you'."
The 65-year-old musician – who raises 17-month-old son Zachary with partner David Furnish – is now believed to have been discharged and is recovering at home.
The star's Million Dollar Piano residency shows are named after the piano he uses. The instrument was custom-made for him by manufacturer Yamaha over four years and cost a reported $1-million to produce.