First round leaderboard-6 W Simpson-5 H Stenson (Swe)-4 R Moore-4 C Wood (Eng)-4 T Woods-4 K BradleyAKRON. It was case of love at first sight for Webb Simpson on his debut at the WGC-Bridgestone Invitational as he spectacularly charged into a one-shot lead in Thursday’s opening round.While seven-times winner Tiger Woods also made a strong start, firing a four-under-par 66, Simpson seized control of the elite World Golf Championships (WGC) event with an eight-birdie 64.On a breezy day of sunshine and sporadic cloud cover at Firestone Country Club, former U.S. Open champion Simpson was in sizzling form on the greens, totaling only 22 putts to end the round a stroke in front of Swede Henrik Stenson.Woods, who has triumphed a season-high four times on the 2013 PGA Tour, mixed six birdies with two bogeys to sit a further shot back, level with fellow Americans Ryan Moore and defending champion Keegan Bradley, and Englishman Chris Wood.Former world number one Luke Donald of England bogeyed his final hole, the par-four 18th, to card a 67 and end the round alongside Americans Bubba Watson, Jason Dufner, Rickie Fowler, Bill Haas and Jim Furyk.Simpson was elated to be the tournament’s front-runner after taking full advantage of advice from his experienced caddie on how to play the heavily tree-lined Firestone layout."It was a great start,” the 27-year-old American told reporters after setting the tone for a low round on a rain-softened layout with four birdies in his first nine holes.IMPROVING FORMSimpson has not triumphed on the PGA Tour since he clinched his maiden major victory at the 2012 U.S. Open but he has been happy with his improving form on the circuit this season.Simpson has recorded four top-10s in 18 starts on the 2013 PGA Tour, his best finish a playoff loss to Northern Ireland’s Graeme McDowell at the RBC Heritage in April.Woods has certainly had the results with four PGA Tour wins this season and he swiftly moved into familiar territory at Firestone, covering his back nine in four-under 31 to rocket up the leaderboard."I felt pretty good today,” said the 14-times major champion. "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. I thought I putted well.”Woods has won a record seven times at Firestone, and has piled up a staggering 11 top-10 finishes in 13 appearances at the elite event.Northern Irish world number three Rory McIlroy returned a roller-coaster 70 while newly crowned British Open champion Phil Mickelson opened with a 72 to sit joint 41st in the 73-man field."Some good, some bad,” McIlroy said after carding five birdies, three bogeys and a double at the par-four 10th. "I felt like I hit a lot of good shots out there.