Aussie Marc Leishman shot a superb six-under 64 to take the first-round lead at the WGC-Bridgestone Invitational.
The Aussie, who finished with a 65 to take fifth place in The Open Championship on his last start, continued his hotstreak with a round that included eight birdies.
Leishman leads by one from England's Justin Rose, South African Charl Schwartzel and American Ryan Moore, who returned 65s on the par 70 in Akron.
Tiger Woods - an eight-time winner at Firestone - hit several wild and wayward shots - but produced plenty of good golf too to shoot a two-under 68.
That was one better than new Open champion Rory McIlroy, who mixed four birdies with a bogey and a double bogey in a 69.
Moore and Schwartzel had set the target with their morning 65s but Leishman was able to reel them in. Starting at the 10th, he made four birdies and a single bogey on his opening nine and joined the lead with two more on the second and fourth. A third straight three put him into the outright lead on six-under before he gave the shot back at the very next hole.
However, a nine-foot birdie putt returned him to the top on his own again and a par at his final hole secured him the day one lead.
Rose, meanwhile, was the pick of the afternoon wave and moved into a tie for second with three birdies in his final four holes as he nailed putts from 14ft, 25ft and 14ft.
The 2013 US Open champion said: "I'm really happy with that number because it wasn't the most in-control round of golf. The scorecard will tell you something different but I got into some trouble a couple of times. Around these greens you can get some really gnarly lies where even if it looks like a simple up and down it's never a simple up and down so I kept the scorecard clean.
"It was a really good mix of some good iron play and then some good scrambling when I missed so that's what you have to do out here."
Tiger's day started with a clumsy three-putt for bogey at the first and then looked set to get worse when he sprayed a drive that went 100 feet left of the second fairway.
A brilliant recovery with his second shot actually gave him a look at eagle before the defending champion two-putted for birdie.
A run of three birdies in four holes from the eighth saw him climb to two-under before he his momentum was halted with a double bogey at nine.
Woods recovered those shots with birdies at 10 and 16 and said later he was happy with his performance.
"I hit a lot of good shots today," said Woods. "I hit a few not so solid but I kind of got it around a little bit. Every time I dropped a shot I got it right back at the very next hole so bouncing back like that was nice.
"It takes time when you're off for an extended period of time and coming off surgery. It takes time, it's been building and today was certainly a lot better."
McIlroy three-putted the third hole - his 12th - and ran up a double-bogey six on the eighth after finding a greenside bunker with his approach and taking four more shots to get down.
However, McIlroy finished in style with a brilliant approach to the ninth to set up a birdie from just two feet to finish one under par.
"I didn't want any sort of let down and not just these two weeks, but basically the rest of the season because I've got myself now in a good position in the FedEx Cup (12th), a good position in the world rankings, we've got a major left this year and there's a lot of golf still left to play," said McIlroy, who could reclaim the world number one spot from Adam Scott with his first World Golf Championship victory on Sunday.
"It's great to win a major, great to win the Open Championship but I just want to keep going forward and I'll have plenty of time in December and January to reflect on it and enjoy what I've achieved this year. For now I want to keep going and try to have some more success on the course."
Scott birdied the last to card a one-under 69.