Ben Curtis is in sight of his first victory since the 2003 Open at Sandwich after shooting a bogey-free 67 took Curtis to 19 under par at the Booz Allen Classic and four clear of fellow American Brett Quigley heading into the final round.

Swede Daniel Chopra moved up to joint third, but remained seven strokes behind, while Padraig Harrington's 68 dropped him from ninth to 10th and the Dubliner is now nine shots back.

The third round had been brought forward because of the threat of bad weather, the leaders teeing off at 9am local time in Potomac. The same will apply for today's final round.

While second-placed Jose Coceres had a nightmare time with a 78, Curtis did not look like the player who had such a tough time following his shock victory at Royal St George's.

That was the first major championship of his life and the best he could hope for apppeared to be second - until Thomas Bjorn, three ahead with four to play, bogeyed the 15th, double-bogeyed the 16th and dropped another shot on the next.

The 29-year-old had only one top-10 finish the following year and only two last season, failing to end the year in the tour's top 100 either time.

He has led since an opening 62 this week and a hat-trick of birdies on the front nine on Saturday took him clear.