WATCH: Biggest shock of Rio 2016 - Joseph Schooling stuns Michael Phelps

Rio de Janeiro: Joseph Schooling stunned Michael Phelps to win the men`s 100 metres butterfly final on Friday.

In doing so, he clinched Singapore`s first Olympic gold medal and denied the American a 23rd in the last individual race of his extraordinary career.

Phelps, the defending champion and world record holder who is heading into retirement -- again -- after Rio, finished second in a three-way dead heat with two of his greatest rivals -- South Africa`s Chad Le Clos and Hungary`s Laszlo Cseh.

rewatching Joseph Schooling's race, giving me goosebumps. so proud to hear #SIN 's national anthem at the Olympics! pic.twitter.com/idrXQyDvxv

— Taengbearies (@thebluebearies) August 13, 2016

Joseph Schooling smashes Olympic record to take S'pore's first gold medal https://t.co/eF3OMS0NRe pic.twitter.com/9OCV0eojA1 — Stomp Singapore (@stompsingapore) August 13, 2016

Astonishingly, all three touched out in 51.14 seconds, behind Schooling`s Olympic record 50.39.

Phelps, who now has 27 medals, had been hoping to win the event for the fourth successive Games.

Joseph Schooling qualified with the top time for 100m butterfly final, will race vs Phelps, who he met as a child pic.twitter.com/gfivuaE00N — Darren Rovell (@darrenrovell) August 12, 2016

(With Agency inputs)