"I'm glad I finally played well around here, just in time to leave", he said.
After a bogey from the trees at No. 3, Thomas went at a back pin on the tough fourth hole and the ball bounded over the green in thick rough.
"I'm going to have a chance", Poulter said.
Thomas's round seesawed between six birdies and three bogeys but was good enough to allow him to enjoy a true advantage over pair of players tied for second place - Northern Ireland's Rory McIlroy (who shot a 67) and second-round co-leader Ian Poulter (70) of England on a day when scoring was at a premium on the demanding South Course.
The win is the third for Thomas in the 2018 season, but his first since the Honda Classic in February.
Roared on by the large galleries in her home country, the 22-year-old Hall only took the lead for the first time after a 20-foot putt for birdie at the 16th hole and stayed steady to post 5-under 67. "You kind of get that two, three, four shot lead, it's, I don't know, it's different than one". What made this one special was not only the time that had gone by since his last win, but who was waiting for him behind the 18th green.
"They don't get to come out that often anymore, so this is my first PGA Tour win with him here and it's really special".
"It was pretty special".
"It's really cool", Thomas said.More news: Saudi Arabia expels Canadian ambassador over 'interference'
Here are the seven hottest storylines entering the Championship, where some of the PGA Tour's young stars will try to accomplish historic feats and a few popular veteran players will try to make up ground in the Ryder Cup USA points standings. His grandfather, Paul, played in the PGA Championship here in 1960.
Bhullar holed a 40-yard chip for eagle on the par-5 17th at Natadola Bay Championship Golf Course. His son, Mike Thomas, also is a career club pro in Kentucky and a former PGA of America board member.
Adam Scott's 74 left the 2011 victor at four over and tied for 57th. Olesen matched Johnson's 64 as they both tied for third.
Nervous at the start, Justin Thomas was in full control at the Bridgestone Invitational to the end.
He started his comeback this year ranked outside the top 500 in the world, moved to 50th - and secured his berth in this week's elite event - with his share of sixth place at the Open Championship.
For Thomas, the win serves as valuable momentum as he heads to Bellerive Country Club next week.
McIlroy won at Bay Hill in March and has three runner-up finishes, and he had said Saturday afternoon he was exhausted of finishing second.
This week's WGC-Bridgestone Invitational, which will be relocated to Memphis next year and called the World Golf Championships-FedEx St. Jude Invitational, is the last scheduled to be played at Firestone Country Club after 65 years on the PGA Tour calendar. He can't say that anymore.