US golfer Arnold Palmer, viewed as one of the greatest players in the sport's history, has died at the age of 87.
Palmer died at the UPMC Presbyterian Hospital in Pittsburgh, Pennsylvania, where he was undergoing heart tests, the Pittsburgh Post-Gazette reported.
The United States Golf Association also confirmed his death in a tweet calling him "golf's greatest ambassador".
During a long career he won more than 90 tournaments worldwide, including seven majors.
Arnold Palmer was the most important golfer to play the game, said the BBC's golf correspondent Iain Carter.
His force of charisma put the game on the map and it never dimmed, he added.
Fellow golfing great and a close friend of Palmer, Jack Nicklaus said he would "miss him greatly".
"We just lost one of the incredible people in the game of golf and in all of sports," he tweeted.
"Arnold transcended the game of golf. He was more than a golfer or even great golfer. He was an icon. He was a legend."
Palmer attracted thousands of diehard fans known as "Arnie's Army" and helped to promote the game into the television age.
"Today marks the passing of an era," said Alastair Johnston, CEO of Arnold Palmer Enterprises bbc.com.