Webb Simpson leads with Tiger Woods on the prowl at Bridgestone Invitational

(CNN) -- Webb Simpson made up for lost time at World Golf Championships Bridgestone Invitational Thursday by firing a six-under-par 64 to move one shot clear at the top of the leaderboard.

Simpson, who missed the tournament last year due to the birth of his daughter, finished the opening day just ahead of Henrik Stenson with Tiger Woods a shot further back.

But Rory McIlroy, who is set to defend his PGA Championship next week, finished six shots off the lead after a double bogey six at the par-four 10th left him with a round of 70.

"With the incredible field it draws every year, you know, this is a tournament you want to be in more than any others with the majors and the FedExCup events," Simpson told the official PGA website.

"You want to play where the best players in the world are playing."

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Simpson, who won the U.S. Open last year, may have produced a series of impressive shots but it was the advice of his caddy, Paul Tesori, which made the difference.

Tesori has caddied for some of the biggest names in golf at Firestone including Vijay Singh and his inside knowledge proved key, according to Simpson.

"It's hard for us players to listen to our caddies, but he basically showed me where to go and told me where to hit it, where the lines were, what clubs to hit," he said.

"I didn't feel like it was my first time because he had so much experience here. You know, had I been with a guy who had never been here, as well, I might have been a little more puzzled.

"We joked about it a little bit yesterday. I haven't listened to him this much since we got together in 2011. But it is nice to kind of have the pressure off me when I'm thinking about stuff."

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Meanwhile, World No.1 Woods, who has won the WGC a record seven times, said he was pleased with his day's work after recording a four-under-par 66.

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"I felt pretty good today," he told reporters.

"It was a little blustery, the wind was up and the greens were soft but at least the ball was flying. I feel very good about what I'm doing with basically my whole swing. I hit a lot of good shots.

"I had a really good feel for the distance today, and (caddie) Joey (LaCava) and I really read the wind right today. We changed a few shots out there, and we both had a really good handle on what we were doing feel-wise with the wind."

The 14-time major winner who last won at Firestone in 2009, rolled in four birdies in his final nine holes to move into contention at the front

"I've played terrible coming in here and I've played really well coming in and, for some reason on this golf course, I just see it," he said. "It's just one of those venues.

"Luckily over the years I've taken advantage of it. I have played well and I've scored well, and I've won my share of tournaments here."