Padraig Harrington endured a mixed start to the Tour Championship but emerged after his front nine just two shots off South African Tim Clark's lead on one-under-par at the East Lake Golf Club in Atlanta, Georgia.
Harrington hit a fine approach at the par-four first but missed his five-foot birdie putt on the high side, apparently reading too much break.
He then hit a shocking tee shot at the par-three second, 20 yards right of the hole, but a deft pitch led to a tap-in par.
The Open champion, who teed off in the first pairing on a muggy day at East Lake, followed with a birdie at the par-four third, sinking a nine-footer after a nice approach shot from the left rough.
A bogey followed on the very next hole before the Dubliner carded a birdie on the par-three sixth and three pars left him at one under at the turn.
Harrington is part of a three-man European contingent, along with Justin Rose and Sergio Garcia, in the 30-man field in the final event of the new play-off series.
Americans Tiger Woods, Steve Stricker and Phil Mickelson are battling for a $10 million bonus awarded to the play-off points winner, while a separate $3.4million purse is up for grabs in the tournament itself.
