Europe's battle for supremacy moves to America this week as Colin Montgomerie and Michael Campbell compete in the WGC-American Express event.
Kiwi Campbell leads the Order of Merit by about £86,000 from Montgomerie, with Retief Goosen, who has pulled out with a groin injury, another £7,000 adrift.
The "Amex", to be held at Harding Park, California, is the third of the year's four World Golf Championship events.
World number one Tiger Woods is bidding for a 10th WGC individual title.
The top 50 players in the world are invited to compete, plus leading players from the world's six major golf tours.
But defending champion Ernie Els, who is still recovering from knee surgery, will be missing from the 71-man field.
"It's very similar to a major championship," said Woods, who won the WGC-NEC Invitational in August.
"We don't get a chance to play against the best very often any more. Everyone plays their own tours.
Woods is chasing a 10th WGC title
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"When we do get together, it's pretty exciting."
Campbell, the US Open champion and winner of the World Match Play, is striving for his first Order of Merit title.
The resurgent Montgomerie, winner of the Dunhill Links event and back to 16th in the world, is chasing an eighth European crown.
But South Africa's two-time winner Goosen, who has been carrying the groin injury for some time, could now face a tough challenge to reclaim the title held by his sidelined countryman Els.
Woods, who won the Masters and Open this year to take his major haul to 10 titles, has won more than $11.6m from nine wins in 18 World Golf Championship starts.
Victory on Sunday on the course he played as a student would put him within striking distance of the single-season earnings record of $10.9m set by Vijay Singh last year.
Woods trails the Fijian's mark by about $2.3m with the winner set to receive $1.3m in San Francisco.
But the 29-year-old insisted adding to his haul of 45 PGA Tour wins was his only goal.
"When I had the record and the money title, it's very misleading," said Woods. "It changes because obviously the purses go up.
"I'd much rather keep having the highest total for wins every year. If I keep doing that, things will be all right."
English trio Lee Westwood, Luke Donald, and David Howell and Ireland's Padraig Harrington are among the other Europeans in action at Harding Park this week.
But Northern Ireland's Darren Clarke has withdrawn to be with his sick wife Heather who is battling cancer.