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 at the start of last year a third title came at The American Express, where he beat Patrick Cantlay by one.
Has also been in three play-offs without success, most recently last August’s Wyndham Championship. Did not play at Royal St George's, preferring instead to focus on the Olympics in Tokyo
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.