WASHINGTON (AFP) — Defending champion Patrick Cantlay fired a six-under-par 65 to open up a one-shot lead at the PGA Tour's BMW Championship in Delaware on Saturday.

Cantlay, bidding to become the first player in FedEx Cup post-season history to successfully defend a tournament title, conjured six birdies and an eagle at Wilmington Country Club for a 54-hole aggregate of 12-under 201.

The 30-year-old world No. 4 started the day two shots adrift of second-round leader Adam Scott but quickly halved that deficit on the opening hole, rolling in a monster 43-foot birdie putt.

Birdies on the third and the seventh — after another long birdie putt from 30 feet — took Cantlay to the turn at three-under for the day.

A bogey on the par-four 11th briefly checked his progress but Cantlay responded with back-to-back birdies on the 12th and 13th before a magnificent eagle three on the 14th, the American holing out with a sublime lob wedge from 104 yards.

That took Cantlay a shot clear of the field at 12 under but a rare putting blunder on the 17th — missing a three-footer for bogey — dropped him back to 11-under.

Yet once again, Cantlay responded in style, blasting his second shot on the 18th to the back of the green with sharp backspin that left him with just a seven-footer for birdie.