• Dustin Johnson one shot behind, Rory McIlroy and Phil Mickelson trail by two • Thomas’s round includes hole in one at the 13th

The tournament narrative for this, the maiden WGC-Mexico Championship, threatened to involve altitude sickness and dodgy empanadas even after the president of the United States insisted kidnap insurance was necessary for competitors.

Rory McIlroy leads WGC event in Mexico at halfway after round of 65 Read more

The counterpoint, and then some, arrived during the finest afternoon of the golfing year thus far. A group of this sport’s leading lights put on a collective display which wowed throbbing galleries and, without question, emphatically justified the decision to switch this tournament from Doral. Old and young, operating under various flags, will joust for the title on what promises to be a riveting day four.

The sense that Dustin Johnson, Rory McIlroy and Phil Mickelson could not excel at the Club de Golf Chapultepec just because the venue is tight and short was again firmly dismissed. This represented a bizarre theory in any case; why would the best golfers in the world all toil on such a traditional layout?

For now the man to catch is Justin Thomas, who is seeking a fourth success of this PGA Tour season. Thomas’s 66 catapulted him to 12 under, a position he will not be altogether comfortable in with Johnson, McIlroy and Mickelson in close proximity. Johnson is one shot back, with McIlroy and Mickelson sharing third at minus 10. McIlroy led by two before a third-round ball was struck, the understandable cause of a rueful look as he stepped from the 18th green.

Johnson’s day began eagle-birdie but was to be punctured by his ball landing in a tree at the 16th. He held a one-stroke lead at that time, with Thomas leaping to the leaderboard’s summit after Johnson’s misfortune was confirmed with a bogey. The world No1 returned a 66, that brush with foliage triggering his only scorecard blemish.

McIlroy’s play was not nearly as free flowing as during the previous 36 holes, perhaps owing to the competitive rust which was always probable after a seven-week absence. The Northern Irishman will hope this 70 represents his worst day of the tournament.

Mickelson chipped in for a birdie at the 1st, the precursor to some flamboyant stuff which included battling through the undergrowth at times. Having received three free drops, one of which came after a sprinkler head was miraculously found in a forest, the left-hander produced a par save at the 14th – duffed shot against a tree and all – which must feature in an all-time back catalogue. Mickelson signed for a 68 which was both ridiculous and wonderful in the context of his erratic play.

Lee Westwood is three years Mickelson’s junior but is still regarded as an elder statesman on tour. Not that he is happy about it. “People keep calling me a veteran, I wish they’d back off with that,” Westwood said with a smile. “I’m not that old.”

Westwood proved his competitive fires still burn brightly with a 66 which moves him to minus nine. Westwood holds the record for WGC appearances with 56 but is seeking a maiden victory, which is now within view. “Well, if you had told me Nottingham Forest would beat Brighton 3-0 today I’d have laughed at you,” said Westwood in reply to whether or not he can prevail here.

Thomas recorded his first hole-in-one when aged just six. He was at it again here, with an ace at the 13th. The dropped shot which immediately followed was offset by birdies at the 15th and 16th. Unlike earlier in his always-promising career, Thomas knows how to respond to minor setbacks. He is also in the midst of some brilliant form.

Jordan Spieth did his best to gatecrash the party with a 63, the lowest round of the tournament, during which he played his closing nine in just 31. At seven under – and given lessons from the past – Spieth cannot be discounted.

The Texan revealed the key to his Saturday charge: not an intense range session after a second round of 72, but YouTube. “This morning I woke up and I watched a couple of videos,” said Spieth. “I wanted to see videos of myself when I thought I was swinging it well. I went to YouTube, I was looking at highlights of a couple of tournaments where I knew I was swinging it well just to see the commitment in the swing and how I could possibly compare.”

The fireworks let off by Spieth and others supplied another point of reference. Sunday has a lot to live up to.