Justin Thomas still held a commanding lead as he reached the turn on day four of the WGC-Bridgestone Invitational but he had World Number One Dustin Johnson breathing down his neck.
American Thomas began the day three strokes clear of nearest challenger Rory McIlroy on 14 under par after producing a superb 67 on a day of tougher scoring on Saturday.
And the 25 year old retained his three-shot advantage after carding one birdie and one bogey on his front nine on Sunday but the chasing pack now featured 2016 champion Johnson, who made seven birdies in his first 16 holes - including four in a row from the first - to jump up to 11 under.
Fellow American Kyle Stanley was also on 11 under after bouncing back from a bogey at the long second with birdies at the fifth, eighth and tenth holes.
Thorbjørn Olesen was the leader in the clubhouse on ten under par after posting a six-under-par 64 in his final round.
Australian duo Marc Leishman and Jason Day were alongside Olesen in a tie for fourth, while McIlroy and Ian Poulter were another shot back on nine under.