Woods proving difficult to catch

Not as sharp as he was Friday when he fired a seven-under 63, Woods managed three pars to start the round before carding a birdie at the par-four fourth.

After two more pars, Woods was at one under on the day and seven under for the tournament.

Scott Verplank was second at four under having matched Woods' birdie at the fourth but run into trouble on the par-five fifth after a drive into the rough and a duffed wedge from 78 yards.

Woody Austin and Geoff Ogilvy were at three under, with Stephen Ames a shot further behind and John Senden one under with no-one else under par.

The field's task of catching Woods is especially daunting and not just because he is the top-ranked player in the world but he is also seven for seven in majors when he has held the 36-hole lead.

Boo Weekley livened up the early action with a stellar round and an error that led to the disqualification of Sergio Garcia.

Weekley came to the 18th hole needing a birdie for a 63 but he left himself a long attempt and three-putted for a bogey and a five-under 65.

However, it was enough to give him the clubhouse lead at level par along with Nathan Green and Kevin Sutherland. Trevor Immelman moved to one over for the championship with a 66.

Garcia would have had a 74 to fall to nine-over but he signed an incorrect scorecard and was disqualified.