Phil Mickelson underlined his determination to remain world number two by matching rival Sergio Garcia's six-under-par 66 in the opening round of the HSBC Champions event in Shanghai.
After winning the Players Championship and October's Castello Masters a Garcia victory in China would see him overtake the American and move in behind runaway world number one Tiger Woods.
Even a top-three finish for the Spaniard, who finished fourth at last week's 2008 season-ending Volvo Masters, could be enough should Mickelson fall back over the final three rounds.
However, there was no sign of the three-time major winner struggling in his first round.
He and Garcia are level with world number eight Anthony Kim and Australian Adam Scott, just one shot behind leader Henrik Stenson.
The Swede kicked off the 2009 European Tour season and money-spinning Race to Dubai in wet conditions at Sheshan International Golf Club but recorded an impressive round of 65.
But much of the focus was on the battle taking place just behind the Ryder Cup star.
"A win last week would have put me to world number two. I think the important thing is that I'm moving in the right direction," said 28-year-old Garcia.
"It would be nice to finish the year as world number two, but if I don't, I've just got to come out next year, come out strong and try and keep playing well and it will come."
While Garcia has one eye on moving in behind the inactive Woods, Mickelson insists he does not even understand the world rankings system and is more concerned about what happens on the course.
The American began the defence of the first title he has won outside his homeland since 1993 with a good opening round, which like Stenson and Kim, included an eagle three at the 550-yard second.
"Certainly Sergio has played some great golf this year," said the 38-year-old left-hander.
"He played wonderful in the FedEx Cup series and he is a tremendous talent but I haven't thought about losing the rankings yet.
"It's the end of the year and my thought is to play well and compete internationally and play well.
"My thought throughout the year is more about trying to win major championships. It's more about trying to play well in the FedEx Cup events at the end of the year and overall improvement."
Garcia also echoed comments made by Mickelson last week about missing the presence of 14-time major winner Woods, who is currently recovering from knee surgery.
"It's never nice to have the top player in your game out for so long," said Garcia.
"We always enjoy competing against Tiger and we know how good he is and how many times he beats us, but at the same time, playing against him is always a great learning experience.
"You can always take a lot of positives out of it, and it's fun to watch him play overall. We miss him so we are looking forward to seeing him next year."
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