Firing a rousing pre-Masters warning, Lee held off golf's biggest names Scottie Scheffler and Rory McIlroy to secure a steely one-shot victory at Memorial Park Golf Club on Monday (AEDT).
World No.1 Scheffler, the second-ranked McIlroy and a swag of other heavyweights stormed home to threaten to crash the in-form Australian's party.
After extending his four-shot third-round advantage to five at one point, Lee's buffer was slashed to one down the stretch after he found the water off the tee on the par-5 16th and Scheffler reeled off four successive birdies.Â
But the Perth prodigy recovered from his first bogey in 41 holes to par the last two to secure the biggest win of his life.
His scrambling par at the 72nd hole, from 54 feet and off the green to inside a foot, symbolised the 26-year-old's grit on championship Sunday.
Lee eventually closed with a three-under-par 67 to post a tournament total of 20-under 260.
Scheffler finished with a typically-sizzling Sunday 63 to share second with fellow American and former US Open champion Gary Woodland.
Woodland had set the clubhouse lead at 19 under with a tournament-record-equalling 62, a brilliant round matched by big Finn Sami Valimaki, who was outright fourth at 17 under.
After starting the day eight shots back, McIlroy had to settle for a tie for fifth at 15 under after conjuring a birdie and six eagles in a round of 64.
But the day and the spoils belonged to Lee, who was stoic and scintillating in equal measures as he warmed up beautifully for the Masters, the year's first major starting at Augusta National in 11 days' time.
12°C