UPDATE 3-Golf-Sizzling Swede Pettersson takes command at Kiawah

* Pettersson fires a 66 to move one stroke clear

* McIlroy, Woodland, Fernandez-Castano and Noren card 67s

* Woods shoots 69 in low-scoring conditions

(Updates at end of round)

KIAWAH ISLAND, South Carolina, Aug 9 (Reuters) - Swede Carl

Pettersson flawlessly put himself in position to improve a

mediocre record in the majors, spearheading a glut of low

scoring to surge into a one-shot lead in the PGA Championship

opening round on Thursday.

The 34-year-old, who became a U.S. citizen in January, fired

a sizzling six-under-par 66 in relatively calm, sunny conditions

at the Kiawah Island Golf Resort to take control of the season's

final major.

Former U.S. Open winner Rory McIlroy, long-hitting American

Gary Woodland, Spaniard Gonzalo Fernandez-Castano and Swede Alex

Noren charged into contention with 67s while four-times champion

Tiger Woods was happy after opening with a six-birdie 69.

Defending champion Keegan Bradley, 1991 winner John Daly and

Dutchman Joost Luiten, who briefly led at eight under before

bogeying his last four holes, were among a group of eight

players who carded 68s at Kiawah, where ocean breezes

strengthened later in the day.

Forty-four players broke par on the longest layout to stage

a major championship, making the most of conditions softened by

heavy rain earlier in the week. The average score was 73.42.

"I played really good," Pettersson told reporters after

breaking 70 for the first time in 21 rounds at the PGA

Championship with an nerveless six-birdie display on a hot and

humid day.

"Getting off to a good start was the key to the round. There

really wasn't much wind on the front nine, so I knew I had to

keep going low because I figured the wind would get up.

"The wind started blowing a little bit on the back nine, and

I carried on solid play, hitting a lot of fairways, hitting a

lot of greens and making a few putts. It was a great day for

me."

Pettersson, who won his fifth PGA Tour title at the Heritage

Classic in April, has missed 10 cuts in the majors while

recording only two top-10 finishes.

"I haven't contended that much in majors ... but I'd love to

have a chance and see what happens," said the Swede, who is

bidding to become the 17th different player in a row to claim

one of golf's grand slam titles.

"You see different people, and some of your friends, winning

majors, and that motivates you. Long way to go, but I'm thrilled

with the start, and we'll see what happens."

STAGGERING WIN MARGIN

McIlroy, who won last year's U.S. Open by a staggering eight

shots, sank a 12-footer to birdie his opening hole, the 10th,

and picked up further shots at the 14th, 16th, second and sixth

to rocket into contention.

"It's a great way to start the tournament," said the

23-year-old Northern Irishman. "Hitting balls on the range this

morning, there was completely no wind. It was flat calm and I

really thought that I had to take advantage of the conditions.

"Very happy with the round. It's a great score to build on."

Most eyes, though, were on Woods who teed off at the 10th in

pursuit of his 15th major title but his first since the 2008

U.S. Open.

Following an early birdie at the 12th he bogeyed the 13th

after finding bunkers off the tee and also with his third shot,

and the tricky par-three 14th, where he missed the elevated

green to the left off the tee.

However, Woods immediately recovered by sinking a 15-foot

birdie putt at the 15th, sparking a cry of "beautiful" from a

fan, before rolling in a 25-footer on the 18th green to prompt

huge roars from the crowd crammed into the grandstands.

Woods also birdied the first and second, stumbled with a

bogey at the fourth, then picked up one more shot at the

par-three eighth to finish three strokes off the early lead.

"I'm pleased," Woods said of his start on the 7,676-yard

Ocean Course. "I played well today and anything in the sixties

is going to be a good start in a major championship. I'm right

there.

"It's one of those days where everyone's going to shoot six,

seven, eight under par, but the wind kicked up a little bit and

it changed things quite a bit.

"If it had stayed pretty benign, I'm sure you would have had

to have shot probably five under par to be in the top 10."

Many of the game's leading players did not fare as well in

the opening round, four-times major winner Phil Mickelson and

Masters champion Bubba Watson grinding out 73s in the tougher

conditions of the afternoon.

British world number one Luke Donald carded a 74,

fourth-ranked Lee Westwood a 75 and U.S. champion Webb Simpson

of the U.S. battled to a 79.

(Reporting by Mark Lamport-Stokes; Editing by Simon Evans and

Frank Pingue)