Rory McIlroy pinpoints switching to old putter as key to hot start to lead at WGC-Mexico Championship

McIlroy insists he has figured out how to play at altitude and is navigating the poa annua greens well at Chapultepec

Rory McIlroy paid tribute to his old putter as the world No 1 made a hot start to lead at the WGC-Mexico Championship after the first round.

The Irishman made the switch at Chapultepec and the move inspired a six-under-par 65, which included an eagle and five birdies – good enough to secure a two-shot lead over Justin Thomas and Bubba Watson.

“It was good, all aspects of my game were working pretty well today,” McIlroy told Sky Sports.

“I drove the ball well and I took advantage of that, but I think the big thing was that I putted well.

“I didn’t putt so well at Riviera last week so went back to my old putter. I was trying a new one last week and it didn’t quite work out the way I wanted to. I was comfortable on the greens today and held some nice ones coming in.”

Rory McIlroy made a fine start in Mexico (Getty)

McIlroy, who played the course in reverse by starting on the 10th, drained a 15-footer for eagle on the par-five 11th, while a solitary bogey arrived at the fourth after misjudging his distance in with his approach.

But a hot finish which included three birdies in his final four holes saw McIlroy propel himself to favourite with three rounds remaining.

The 30-year-old hopes to go one better than 12 months ago when Dustin Johnson edged him out, but the defending champion laboured to an opening round of 76 to sit 11 shots back.

“I’ve always played well at altitude,” McIlroy added. “I finished second in Crans (Omega European Masters) last year, second here last year – I think I’ve got the altitude pretty figured out, I’ve got a pretty good formula for it.

“You have to read it (the poa annua greens) as well as you can, try and start it on your line and if it goes in, it goes in.

“That was sort of the saving grace last week, I knew everyone was struggling on the greens. If a putt misses and you’ve hit a good putt you just have to step up to the next one and try again. That’s what I did today, I had a really good attitude on the greens and it paid off.”