Luke Donald's quest to regain the number one position in world golf from Rory McIlroy remains on course after the third round of the Zurich Classic of New Orleans.
The 34-year-old needs a top seven finish at Avondale to take over at the top of the rankings - and he moved up to eighth with a third round 66, sharing that placing with Ken Duke.
Donald produced birdies at the second, fifth, seventh, 10th, 13th, 14th and 18th holes, with the only blemish on his card a bogey at the par four sixth.
It moves him to within five shots of leader Jason Dufner, who shot five under par in his third round to take a two-stroke lead over Graham DeLaet.
Dufner has not won in 163 starts on the US PGA Tour and is best remembered for losing a play-off to Keegan Bradley in last year's US PGA Championship.
However, he followed rounds of 67 and 65 with another 67 to maintain control of this tournament in Louisiana.
DeLaet shot a 66, while a further stroke back were John Rollins and Ernie Els, who shot 69 and 68 respectively.
Ryan Palmer tied the course record with a 64 to join Steve Stricker and Cameron Tringale at 13 under - but Scotland's Russell Knox slipped out of contention.
Knox, a 26-year-old who was born in Inverness but now lives In Florida, moved into contention with a 64 of his own in the second round but was not in the same form in the third.
His only birdie came at the 18th - but bogeys on the fifth, 12th and 17th made for a disappointing round of 74.
Joining Knox on nine under were defending champion Bubba Watson, playing in his first tournament since winning the Masters - who fired a 65 - and England's Justin Rose (68).
English duo Greg Owen and Brian Davis were three shots back after a 71 and 72 respectively, a shot ahead of Northern Ireland's Graeme McDowell, who was sharing 45th position with 11 other players after a 69 which included six birdies and three bogeys.