World No.1 Tiger Woods is on track for a record eighth World Golf Championships Invitational after a hot start to his second round.

Woods, who started two off the lead, birdied the first, eagled the second and birdied the third to move to eight-under for the tournament, two shots clear of defending champion Keegan Bradley and fellow Americans Jason Dufner and Webb Simpson.

Bradley shot a two-under 68 to grab the clubhouse lead at six-under but might find himself well behind Woods if the 14-time major winning continues his hot form.

Woods has already registered four wins on the US PGA tour this season and has 17 WGC wins in 41 starts in the lucrative events.

He last won at Firestone Country Club in 2009.

Adam Scott remains the best of the Australians with an early birdie in round two but the Masters champion is a distant 10 shots back at a two-over total through four holes.

Jason Day backed up his opening 74 with a 72 to be six-over and tied 62nd while Brett Rumford (+10) and Daniel Popovic (+13 through five holes) occupy the last two places on the leaderboard in the 73 man field.