FIRST-ROUND LEADERBOARD US unless stated -8 V Singh (Fij) -5 R S Johnson (Swe), P Perez, C Beckman, B Curtis, R Allenby (Aus), K Na (Kor) (after 14 holes) -4 J Byrd, L Janzen, T Armour, J Daly, J Sindelar, JP Hayes, K Cox (after 14) Clubhouse scores

With 36 players still to complete their rounds, the world number one fired an eagle and six birdies to head six players by three shots in Pennsylvania.

Victory for Singh would see him surpass Tiger Woods' season money record of $9.1m (�5m) set in 2000.

And with seven tournament wins, the Fijian is closing in on Woods' best season of nine wins.

Singh has carded four rounds of 65 or lower in his last five tournaments, and admits he is playing at his very best.

I'm swinging the club as good as I think I can Vijay Singh

"I'm driving the ball the way I want it," said Singh, who is going for his fifth victory in six tournaments.

"I don't know if I can hit it any better. My playing is pretty good.

"I'm doing the same thing over and over again. I'm swinging the club as good as I think I can."

Singh overtook Woods as world number one after victory at the Deutsche Bank Championship earlier this month and won the Canadian Open in a play-off from former Masters champion Mike Weir two weeks ago. He also won the Buick Open and the USPGA in August.

The 41-year-old leads Sweden's Richard S. Johnson, Americans Pat Perez, Cameron Beckman and Ben Curtis and Australian Robert Allenby by three shots.

Korea's Kevin Na, the youngest player on the PGA Tour at 21, was also on five under after 15 holes when play was suspended due to darkness. The start of play was delayed by 90 minutes because of fog.

All three US Ryder Cup players in the field were below par, with Chris DiMarco and David Toms at two under and Stewart Cink one under through 16.