Dustin Johnson stretched his bogey free run at Chapultepec Golf Club to 57 holes as he turned in 32 to open up a five shot lead on day three of the WGC-Mexico Championship.
The American was blemish-free in his last 12 holes here last season and he was yet to drop a shot this time around as he moved to 14 under.
Northern Ireland's Rory McIlroy was his nearest challenger, a shot clear of Spaniard Sergio Garcia, England's Ian Poulter and Masters Champion Patrick Reed.
Johnson has won this event twice - including here in Mexico City two years ago - and is looking for a sixth World Golf Championships title this week.
McIlroy went a long way right off the first tee, finding sand with his second for a bogey, and while he went right again off the second tee he got up and down from a fortunate lie to bounce back.
That left him four behind playing partner Johnson, however, as the 34-year-old drove the green to leave himself four feet for an eagle and a four shot lead.
McIlroy's bounceback continued as he made a 20-footer from the fringe at the par three third to get back into double figures but an approach to eight feet on the fifth restored Johnson's four shot lead.
A three-putt from McIlroy on the seventh then put Johnson five ahead and another bogey after a poor tee-shot on the next dropped the 29-year-old into a share of second alongside Garcia and Reed.
Garcia had put an approach to two feet on the second but three-putted the third and made another bogey after a clumsy tee-shot on the fifth. He then bounced back by taking advantage of the par five seventh and holing a 19 foot right-to-lefter on the seventh.
Reed came up just short of the first green but got up and down before chipping in at the second for an eagle and a fast start. A three-putt on the fourth stalled his momentum but he made the most of the sixth, holed a 27-footer on the ninth and eagled the par five 11th after getting on the green in two.
Poulter drove the green on the first and got down in two but then made eight pars in a row before a 16 foot putt on the tenth moved him into that share of second.
McIlroy's luck seemed to be out when he hit the pin on the ninth and ended up 34 feet from the hole but he made the putt to break out of the logjam at eight under and cut the lead back to five.
Patrick Cantlay, Tommy Fleetwood, Louis Oosthuizen and Cameron Smith were seven shots off the lead.
