The 34-year-old world number three has won the event twice previously and now leads this year's competition at the Chapultepec Golf Club in Naucalpan.

Today he shot a four-under-par 67 to take the lead from Northern Ireland's Rory McIlroy.

McIlroy was four shots clear at one stage today but is now in joint second with American Matt Kuchar after a four-putt double bogey in a round of 70.

"These greens, with a bit of traffic on them, get a little crusty and it's hard to trust your lines, but I'm still in a good position," he said, as reported by BBC Sport. 

Defending champion Phil Mickelson of the United States is struggling in his campaign to retain his title, but has moved up to joint 39th place after he birdied the first three holes of his second round and returned a 65.

American 14-time major winner Tiger Woods has climbed up the standings on what is his professional debut in Mexico.

He shot a five-under-par 66 to move from joint 25th place to joint eighth. 

The action in Mexico will continue tomorrow.