By Mark Lamport-Stokes

AKRON, Ohio (Reuters) - Thailand's Prayad Marksaeng birdied his first three holes on the way to a share of the early lead with South African Tim Clark in the WGC-Bridgestone Invitational first round on Thursday.

Competing in the elite World Golf Championships (WGC) event for the second year in a row, Prayad took advantage of ideal morning conditions at Firestone Country Club to fire a four-under-par 66.

Although the six-times Asian Tour champion bogeyed his last two holes, the eighth and ninth, he remained at the top of the leaderboard with Clark, who mixed six birdies with two bogeys.

U.S. Ryder Cup player Steve Stricker carded a 67 while fellow American Hunter Mahan, Australian Robert Allenby and Spaniard Miguel Angel Jimenez opened with 68s.

American world number two Phil Mickelson, back on the PGA Tour after a six-week break while supporting his wife and mother as they undergo breast cancer treatment, returned a level-par 70.

Top-ranked Tiger Woods, bidding for a record seventh title at Firestone, was among the late starters.

Prayad was delighted with his display after teeing off in the second group of the day on the par-four 10th hole.

"Conditions were very nice and I was really happy with my start," the 43-year-old told reporters, speaking through an interpreter. "The greens were quite fast but I like them fast.

COMFORT FACTOR

"When I came here last year, I felt really comfortable with the course. It's very similar to the Japanese golf courses that I played on the Japan Tour."

Clark, who tied for sixth at Firestone two years ago after previously struggling on the tree-lined layout, said he had benefited from adopting a more positive attitude at the venue.

"I used to get quite frustrated around here because I felt like I'd hit a lot of good tee shots and the ball would just kick off into the rough," the three-times European Tour winner said.

"The rough used to be a lot thicker here and that made it really tough for a guy like me," added Clark, one of the shorter hitters on the circuit.

"But now I try to come here with a refreshed attitude and try to enjoy myself. It's a good setup and it's going to reward good play."

(Editing by Justin Palmer)