World Number Three Hideki Matsuyama was among the early leaders on day one of the WGC-Bridgestone Invitational but a host of European Tour Members were within touching distance at Firestone Country Club.
Matsuyama and American trio Charley Hoffman, Jimmy Walker and Bubba Watson were all at three under, with Japan's Hideto Tanihara, Scot Paul Lawrie and South African Shaun Norris all in the group a further shot back.
Starting from the tenth, Matsuyama birdied his opener but gave the shot straight back before a hat-trick of gains from the 13th moved him into the share of the lead.
Walker had birdies on the 11th, 14th and 16th in his first seven holes while Watson made gains on the tenth, 13th and 16th.
Hoffman made a flying start, birdieing the first, second and third and Lawrie was also impressive starting from the tenth.
The 1999 Open Championship winner put his approach to eight feet and then went even better on the 11th, getting inside four feet to sit one off the lead.
Norris had played eight holes and eagled the second after putting his second to six feet and, while he bogeyed the next, he picked a shot back up on the par three seventh.
Tanihara also took advantage of the second, making a birdie, and an 18-foot putt on the fourth moved him to two under.
Zach Johnson and Jhonattan Vegas were also a shot off the lead.
There were then 17 players at one under including Russell Knox, Chris Wood, Thomas Pieters, Alex Noren, Thorbjørn Olesen, Henrik Stenson and Andy Sullivan.
Starting from the tenth, Matsuyama birdied his opener but gave the shot straight back before a hat-trick of gains from the 13th moved him into the share of the lead.
Walker had birdies on the 11th, 14th and 16th in his first seven holes while Watson made gains on the tenth, 13th and 16th.
Hoffman made a flying start, birdieing the first, second and third and Lawrie was also impressive starting from the tenth.
The 1999 Open Championship winner put his approach to eight feet and then went even better on the 11th, getting inside four feet to sit one off the lead.
Norris had played eight holes and eagled the second after putting his second to six feet and, while he bogeyed the next, he picked a shot back up on the par three seventh.
Tanihara also took advantage of the second, making a birdie, and an 18-foot putt on the fourth moved him to two under.
Zach Johnson and Jhonattan Vegas were also a shot off the lead.
There were then 17 players at one under including Russell Knox, Chris Wood, Thomas Pieters, Alex Noren, Thorbjørn Olesen, Henrik Stenson and Andy Sullivan.
