Francesco Molinari moved into a share of second, but Adam Scott left the field trailing in his wake as he closed in on a victory in the Arnold Palmer Invitational which could see him defend his Masters Tournament title as World Number One.
Scott held a three shot lead after a stunning opening ten under par 62 at Bay Hill, which equalled the course record held by Andy Bean and his fellow Australian Greg Norman.
And the 33 year old extended his advantage to seven strokes with a second round of 68, marred only by bogeys on the seventh and 18th, where he three-putted from long range.
Victory on Sunday would leave Scott fractionally behind the absent Tiger Woods in the Official World Golf Ranking, but if neither man played again before Augusta National, Scott would assume top spot for the first Major of the year.
Italy's Molinari and American duo JB Holmes and Chesson Hadley were Scott's closest challengers on seven under par, with Welshman Jamie Donaldson carding a 71 to lie six under alongside former US PGA Champion Keegan Bradley and Brandt Snedeker.
Ian Poulter also returned a 71 to lie five under, but it was not such a good day for his Ryder Cup team-mate and fellow Orlando resident Graeme McDowell, who followed his opening 68 with a second round of 77 that did not feature a single birdie – although he at least made the cut on one over par.
