Y.E. Yang moves into the lead at Sherwood

Y.E. Yang is best known for beating Tiger Woods in the final round to win this year’s PGA Championship, so it seemed only fitting that the South Korean again would make ripples at Woods’ tournament.

Yang overcame flu symptoms and fired a seven-under-par 65 on Friday to take the second-round lead in the Chevron World Challenge, which benefits Woods’ charity.

That gave Yang a two-day total of nine-under 135 at the par-72 Sherwood Country Club in Thousand Oaks.

Two shots behind Yang were three golfers: two-time British Open champion Padraig Harrington, who won this tournament in 2002; Ian Poulter, who shared the first-round lead; and Kenny Perry, who matched Yang’s 65 as Perry concludes what has been, in his words, “a magical year” on the golf course.

The 49-year-old Perry was a two-time winner on the PGA Tour this season, and he nearly became the oldest player to win the Masters before losing in a playoff to Angel Cabrera.

Friday’s round “was kind of a continuation of the year,” Perry said, even though he took a month off from golf in November and “really didn’t have any expectations” coming into this week’s tournament.

A trio of golfers was three shots behind Yang: former Masters champion Zach Johnson, who shared the first-round lead with Poulter; Lee Westwood, who shot 67 on Friday; and Sean O’Hair.

At four under was Graeme McDowell, who was a late addition to the 18-player tournament -- which pays $1.35 million to the winner -- after Woods withdrew amid the personal problems that have engulfed the world’s No. 1 golfer.

Yang, 37, earned his first PGA Tour victory at the Honda Classic in March, then stunned the golf world in August when he held off Woods for the PGA Championship at Hazeltine National in Chaska, Minn.

It was the first time in 15 major tournaments that Woods had lost an event after holding a 54-hole lead.

On Friday, Yang’s biggest challenge was ignoring how sick he felt. “I’m actually coming down with a flu or a fever, I don’t know which one it is,” along with a “pounding headache,” Yang said through an interpreter.

As a result, “I didn’t try to force anything,” said Yang, who was at PGA Tour qualifying school last year at this time. “Somehow I rolled in a few putts, so it resulted in a good round today.”

But Yang added that he “wasn’t 100% satisfied” with his play, which included hitting 14 of 18 greens in regulation. “It just seems that I’m missing out on something right now.”

With course conditions and the weather again ideal, scores fell sharply at the 7,027-yard Sherwood course, with only five of the 18 players failing to break par.

McDowell had an especially up-and-down round. He birdied the opening three holes, bogeyed Nos. 7-8-9 and then birdied the next three holes to move into contention.

james.peltz@latimes.com