Extra spice has been added to this week's WGC-Bridgestone Invitational, where Tiger Woods is in danger of being dethroned as world No.1 by either fellow American Phil Mickelson or Britain's Lee Westwood.

Mickelson would take over at the top for the first time with victory at Firestone Country Club on Sunday, as would a triumphant Westwood if Woods finishes worse than in a two-way tie for second place.

Regardless of the various permutations which could pan out, Woods is solely concerned with trying to win his first tournament of the year and a record eighth title at the venue.

"You just keep playing," the 34-year-old American said on the eve of Thursday's opening round. "How I got here in the first place was by winning golf tournaments, and how I will sustain it is by winning golf tournaments. Winning golf tournaments takes care of a lot of things and being No 1 is one of them."

Woods, a 14-time major winner, has been golf's leading player for the last 270 weeks and for an overall total of 612 weeks in his illustrious career. However, he has not won a tournament since the Australian Masters in November.

Second-ranked Mickelson has yet to reach the mathematical pinnacle of the game but, like Woods, he preferred to concentrate on tournament play.

"It would mean a lot to me, but it's not something I'm focusing on as much as trying to get my game sharp for these upcoming events," the US Masters champion said. "These next two weeks, Akron and the PGA (Championship), are special events not because it provides an opportunity to become No 1.

"If I were able to come out and win the PGA, I would take a year that's been special and memorable and make it one of the best years in my career."

Asked if he felt any extra pressure in his bid to reach the top spot for the first time, Mickelson replied: "I don't know."