Shanghai - Tony Finau charged into a three-stroke lead at the midway point of the WGC-HSBC Champions on Friday with a splendid five-under 67 that was slowed only by an improbable hard-luck bounce off a sprinkler head.
Finau had snatched the lead from overnight front-runner Patrick Reed and was pulling away after birdies on five of the first 10 holes despite swirling winds at Shanghai's Sheshan International Golf Club.
But his approach on the par-four 11th landed smack on a greenside sprinkler and bounded past the hole into a hazard, leading to double-bogey.
"That's about as bad a break as I have ever had. But one thing I learned from this game is you take the good with the bad," Finau said with a laugh.
But the 29-year-old American, whose fast-improving game has vaulted him up the golf world rankings to 17th, righted the ship with three birdies down the stretch.
"I knew I was still playing well and there was a lot of golf to be played," said Finau, who proved an inspired captain's pick for the USA in last month's crushing Ryder Cup loss to Europe.
The first player of Polynesian descent to play on the PGA Tour, Finau totalled eight birdies to move to 11-under, with Reed at eight-under after managing only par for the day.
Tied with Reed were defending champion and world number three Justin Rose and fellow Englishman Tommy Fleetwood.
Rose, who came from eight shots back in the final round last year to lift the trophy, was feeling good after not dropping a shot all day on the way to a five-under 67.
"Those rounds don't often come, especially in breezy conditions," said Rose, who will tee it up with Finau and Reed on Saturday.
American Xander Schauffele finished four strokes behind Finau after managing a one-under 71 in winds he said were "all over the place."
"If you look at the leaderboard, no one is really running too far away with it, so it's nice to not go the opposite way today," Schauffele said.
After a dominating opening-round 64, reigning Masters champ Reed had to scramble on Friday as he found water three times.
But the famously competitive Texan pulled off the shot of the day to avoid what he said could have been a "big number" on the par-five 18th.
After slicing his drive into the water, Reed faced a difficult third shot from a downhill lie and with about 220 yards to the green. Rather than lay up, he went for it, fading a gutsy shot over the water which rolled to a few feet from the pin.
He just missed the birdie putt.
"After hitting the tee shot in the water, you're always happy to be able to walk off with par," he said.
Other big names failed to deliver the goods in a tournament dubbed "Asia's major" and which annually gathers a premier field with its winner's purse of $1.8 million.
Newly crowned world number one Brooks Koepka struggled to a 74 to enter the weekend at two over par, while the man he replaced as the planet's top-ranked player, Dustin Johnson, was another stroke behind.
Four-time major winner Rory McIlroy followed his opening round even-par 72 with a 77 to sit well off the pace.
Leading scores after the second round of the $10 million WGC-HSBC Champions in Shanghai on Friday:
133 - Tony Finau (USA) 66-67
136 - Patrick Reed (USA) 64-72, Justin Rose (ENG) 69-67, Tommy Fleetwood (ENG) 68-68
137 - Xander Schauffele (USA) 66-71
138 - Patrick Cantlay (USA) 70-68
139 - Kiradech Aphibarnrat (THA) 68-71, Keegan Bradley (USA) 69-70, Emiliano Grillo (ARG) 70-69, Pat Perez (USA) 70-69, Kyle Stanley (USA) 70-69, Thomas Pieters (BEL) 75-64
140 - Ian Poulter (ENG) 69-71, Ryan Fox (NZL) 70-70, Billy Horschel (USA) 68-72
141 - Rafael Cabrera Bello (ESP) 68-73, Paul Casey (ENG) 73-68, Alexander Levy (FRA) 71-70, Andrew Putnam (USA) 70-71, Jason Day (AUS) 71-70