Leading first-round scores on Thursday in the World Golf Championships Mexico Championship at Club de Golf Chapultepec (USA unless noted, par-71): 65 - Rory McIlroy (NIR) 67 - Bubba Watson, Justin Thomas 68 - Louis Oosthuizen (RSA), Billy Horschel, Corey Conners (CAN), Bryson DeChambeau 69 - Tyrrell Hatton (ENG), Paul Casey (ENG), Patrick Reed, Im Sung-jae (KOR), Lee Westwood (ENG), Hideki Matsuyama (JPN) 70 - Abraham Ancer (MEX), Tommy Fleetwood (ENG), Gary Woodland, Bernd Wiesberger (AUT), Erik van Rooyen (RSA) 71 - Lucas Glover, Rafa Cabrera Bello (ESP), Pablo Larrazabal (ESP), Branden Grace (RSA), Chez Reavie, Zach Murray (AUS), Justin Harding (RSA), Sebastian Munoz (COL), Kevin Na, Matthias Schwab (AUT) afp