Marana, Arizona - While three-times winner Tiger Woods was in early trouble, Yang Yong-eun drew first blood in Wednesday's opening round of the WGC-Accenture Match Play Championship by beating Graeme McDowell 2&1.
South Korean Yang birdied four of the first seven holes at Dove Mountain's Ritz-Carlton Golf Club before sealing victory with his seventh birdie of the day at the par-four 17th.
"I ran into a man that played extremely well," Britain's Graeme McDowell told reporters. "I felt like I had to follow him all day long, and I did most of the day, but he didn't put a foot wrong.
"I made six birdies today. You just run into the wrong guy on the wrong day, and you have got your work cut out. I didn't take care of business, so I'm disappointed, yeah."
Soon after Yang's win, Japan's Ryo Ishikawa came from three down after 13 holes to beat American Bill Haas one up before Paul Lawrie edged fellow Briton Justin Rose by the same margin on a breezy, sun-splashed day in the Arizona desert.
Ishikawa birdied 14, 15 and 17 before wrapping up victory on the 18th green against an in-form opponent who won the PGA Tour's Northern Trust Open on Sunday in a playoff.
"Through the first 13 holes, it was really tough and I wasn't playing that well," Ishikawa said through an interpreter. "But the last five holes, I was able to compete with the opponent. This course is suited for me."
Three-times major winner Woods, seeking his first victory on the US circuit in over two years, was one down to Spaniard Gonzalo Fernandez-Castano after six holes.
Fernandez-Castano, who described the 14-times major champion as "beatable" during the build-up to this week's event, holed putts from 13 and 22 feet to birdie the first two holes.
His birdie at the par-five second was astonishing as he hit his drive well right into a small bush before striking a superb second shot to just short of the green and then getting up and down.
However, the Spaniard bogeyed the par-four fifth after missing the fairway to the right for his lead to be cut to one up.
In other matches, Americans Hunter Mahan and Zach Johnson were all square after 18 holes and Masters champion Charl Schwartzel of South Africa was three up on American Gary Woodland after 15.