In 2017 became the youngest-ever winner of the Players Championship at 21, beating Ian Poulter and Louis Oosthuizen by three when ranked 75th in the world.
It was his second PGA Tour victory – in 2016 he finished five clear of Luke Donald at the Wyndham Championship after posting a second-round 60 – and he has had two more since then, most recently January’s Sony Open in Hawaii, where he closed with back-to-back rounds of 64. He has also been in three play-offs without success.
Did not play at Royal St George's in 2021, preferring instead to focus on the Olympics in Tokyo, but last July he tied for 15th at St Andrews.
Aged 17 in 2012 he was the youngest player to survive the PGA Tour qualifying school, but could not join the circuit until his next birthday.
Two years later he was the second youngest winner – behind Jason Day – on the Web.com Tour and while Henrik Stenson was winning the Claret Jug at Royal Troon in 2016 he finished runner-up to Aaron Baddeley at the Barbasol Championship.
Made his Presidents Cup debut in 2017 and was part of the South Korean side that finished joint third in the 2012 world amateur team championship.