(Reuters) - Lee Westwood spoke about his "ballistic" ball after bogeying the final two holes to fall into a share of the lead with Phil Mickelson and four others after the first round at the WGC-Mexico Championship at Club de Golf Chapultepec in Mexico City on Thursday.
The 43-year-old Englishman led by two strokes before stumbling at the end, while Mickelson rolled in a 16-footer for birdie at the last to join him with a four-under 67.
Former world number one Westwood was generally pleased with his performance, though he was punished a couple of times when his ball carried further than expected in the thin air more than 2200 metres (7200 feet) above sea level.
"I played great," Westwood told Golf Channel. "It's a tricky golf course. It's hard work playing at altitude. Occasionally one just goes ballistic and you end up in a nightmare of a spot."
Mickelson also spoke about how far he was hitting the ball after his birdie finish left him atop a leaderboard that also included PGA Championship winner Jimmy Walker, fellow American Ryan Moore, Englishman Ross Fisher and young Spaniard Jon Rahm.
The six-way tie for the lead marked a record for a World Golf Championships stroke play event dating back to the inception of the series in 1999.
"This is an incredible challenge for all of us," Mickelson said about the heavily tree-lined course, adding that he could hit a nine-iron more than 180 yards.
"At sea level I might hit a nine-iron 150 yards. If I need to hit it a little harder I might be able to get 155 out of it. Let's say I hit it 170 here, if I want to get a little more out of it, I can get 10-to-15 more yards, I can hit it 180, 185."
Rory McIlroy, in his first competitive round after a six-week layoff due to a rib injury, was among seven players one shot from the lead.
"My first full competitive round today and I didn't feel it at all," world number three McIlroy said about his ribs. The Northern Irishman was more concerned about an upset stomach that he said left him feeling a bit weak during the round.
Sweden's British Open champion Henrik Stenson fell foul of the same condition and withdrew after 11 holes, leaving 76 players in the elite field that boasted 49 of the top 50 in the world, with only number two Jason Day (ill) absent.
American Dustin Johnson, making his first start as world number one, shot 70 despite missing seven putts within seven feet.
"Obviously, I didn't score very well at all, but I played really well," the long-hitting Johnson said. "I missed so many putts, short ones. Six of those seven were inside five feet."
(Reporting by Larry Fine in New York; Editing by Andrew Both)