Singapore exploded in celebration Saturday after homegrown swimming hero Joseph Schooling beat US legend Michael Phelps in the 100m butterfly in Rio to win the tiny republic's first ever Olympics gold.

The 21-year-old Asian champion set a new Olympics record of 50.39sec as he edged out his American idol Phelps, who ended in a sensational dead heat for silver alongside South Africa's Chad le Clos and Laszlo Cseh of Hungary.

Prime Minister Lee Hsien Loong and President Tony Tan, who was in Rio to cheer Team Singapore, led an outpouring of congratulations for Schooling, whose mixed European and Asian heritage has resonated in the immigrant society of 5.5 million people.

"It is an incredible feat, to compete among the world’s best, stay focussed, and emerge victorious," Lee said in a Facebook post.

Schooling will receive Sg$1.0 million ($743,000) for his gold medal as part of a programme aimed at encouraging studious Singaporeans to excel in sport.

Schooling pulled off one of the biggest upsets in Rio, interrupting the 31-year-old Phelps' quest for what would have been his fifth gold in Brazil and 23rd Olympic gold in his career.

The American phenomenon, who insists he won't be back for a sixth Olympics, has a shot at one more gold in Saturday's 4x100m medley, before retiring as the greatest Olympian of all time.

Schooling meet Phelps when the US Olympics swim team was visiting Singapore in 2008, and the American helped inspire the young Singaporean to move to the United States for extensive training. Schooling is now based at the University of Texas.

Singaporean social media erupted in celebration as Schooling won in Brazil, as cheers broke out in public housing estates, where most Singaporeans live. Many people had woken up early to watch the event live.

"Finally! We have done it at the grandest of stages!" Jayarethnam Pillai wrote on the prime minister's Facebook page.

Schooling's father Colin, who hosted a viewing party at his home in Singapore, wept when his son won the medal.

"If I cry in front of all of you all, it's because I have nothing to be ashamed of," he told reporters.

"My love for my son is nothing I can describe to you all."

In 2014, Colin Schooling dismissed stubborn speculation that his son was a "foreign talent" because of his surname -- declaring that Joseph, a third-generation Singaporean, was a true son of the republic.

A programme to import sporting talent into Singapore has proved controversial, despite helping the country to win medals in regional and international competitions.

Chinese-born female table tennis players who were naturalised by Singapore won a team silver at the 2008 Beijing Olympics and an individual bronze in London 2012.

Singapore's first Olympics medal was won by weightlifter Tan Howe Liang, who bagged a silver in Rome in 1960.

Source: AFP