An eight-under opening round of 64 saw Justin Thomas make a strong start to his defence of the CIMB Classic in Malaysia on Thursday.
Thomas won his first PGA Tour title at the event in Kuala Lumpur last year, fending off Adam Scott by one shot.
He shares the lead at the Kuala Lumpur Golf and Country Club's West Course alongside fellow Americans Keegan Bradley and Derek Fathauer.
Paul Casey, who has finished in the top four in his last four starts, shot a seven-under 65 to sit outright fourth.
The in-form Englishman is still searching for his first win since the KLM Open in 2014.
Sergio Garcia carded a five-under 67 to be tied sixth in his first competitive appearance since impressing in vain as Europe lost the Ryder Cup at Hazeltine National, carrying his good form over into this event.
And Scott, who missed his first cut in over a calendar year at last week's Japan Open, as he fought off some of the rust from his impressive FedEx Cup playoffs run, shot a two-under 70 to be tied 26th.