Padraig Harrington produced a barnstorming finish to card a seven-under-par 63 in the opening round of the Tour Championship here yesterday.

The Open champion took advantage of ideal conditions after a three-hour rain delay, picking up birdies at the final four holes to come within one shot of the East Lake course record. He was one stroke behind South African clubhouse leader Tim Clark on a day when only 10 players in the 30-man field finished, due to the long stoppage.

Harrington, who completed 12 holes before the delay, came out firing. He had a tap-in birdie at the par-five 15th before sinking a 15-footer at the par-four 16th. He then jammed home 10-footers at the final two holes to negotiate the back nine in 29 strokes.

"I don't think I would have been capable of doing this if I played last week," said Harrington, who skipped a play-off event, citing tiredness. "I did a lot of good things, and that's the sign of a player who's fresh."

Tiger Woods made a good start, four under after 11 holes, while Justin Rose was two under after 15 holes, with Sergio Garcia two under through 13 holes.

Woods, who hit his approach shot to the first green shortly before bad weather halted play for three hours, could do nothing wrong for a while when play finally resumed.

While Woods lamented the bumpy greens, Harrington said they reminded him of the putting surfaces in Ireland after the winter months. "I'm pretty familiar with them, especially at this pace," he said.

His putter running hot on the soft, slow greens, he birdied the first three holes in his quest to win the $10m (£4.9m) bonus awarded on Sunday to the FedEx Cup play-off winner.

Woods leads the points list, with his fellow Americans Steve Stricker and Phil Mickelson his only realistic challengers.