American Jason Dufner set a new Oak Hill course record and also became the 24th player in the history of the Majors to shoot a round of 63.

Dufner played a superb shot into the final green but then agonisingly left his birdie attempt some three feet short before, and to the relief of all those watching, hole his par putt.

It put the 2010 PGA Championship runner-up into the lead by a shot on nine under par.

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