McIlroy has won three WGC events in addition to his four major WGC-Mexico Championship first round leaderboard-6 R McIlroy (NI) titles; -4 B Watson (USA), J Thomas (USA); -3 L Oosthuizen (SA), B Horschel (USA), C Conners (Can), B DeChambeau (USA) Selected others: -2 T Hatton (Eng), P Casey (Eng), L Westwood (Eng), P Reed (U.S); -1 T Fleetwood (Eng); +1 M Fitzpatrick (Eng); +5 G McDowell (NI), D Johnson (US)
World number one Rory McIlroy played a six-under-par 65 to take a lead of two after the opening round of the WGC-Mexico championship.
The Northern Irishman, 30, last year second to Dustin Johnson, started from the 10th and peeked his second hole, before three birdies in his last four.
American left-handed Bubba Watson had a career-best 21 putts and shares second with world number four Justin Thomas.
However, Johnson ran four bogeys and a double bogey in a five-over 76.
McIlroy, who won the WGC-HSBC Champions in Shanghai in November for his 18th PGA title, hit one some typically huge rides and sparkling iron shots, but also dropped some long putts in the Club de Golf Chapultepec.
On the 520-yard par-four eighth, he hit a disc and eight iron and ran out of the back of the green, for a wedge of up to nine feet in the last set of his fifth birdie of the day.
"All aspects of my game worked well, the great thing was that I put well," said McIlroy, who returned to a former putter who had experimented with a new one at the Genesis Invitational last week when he was in the final round went out to a 73 and finished fifth.
Paul Casey from England drove the green to be the first to advertise the 303 yard – his 10th – and is second to fellow countrymen Tyrrell Hatton and Lee Westwood.