US Tour Bay Hill Invitational: Tiger Woods needed six months to reclaim the number one world ranking, though keeping it could prove a tough task at this week's Bay Hill Invitational against Vijay Singh and Ernie Els.

Singh, who lost top spot to Woods two weeks ago at the Doral, and Els arrive at Orlando's Bay Hill Club today looking to bring the American's reign to a quick end.

Woods, however, appears back to the form that has brought him eight majors, and is chasing a fifth victory in six visits to Bay Hill, so dislodging him will be a daunting challenge.

Either scenario, the stage is set for another pulsating showdown with Woods, Singh and Els - the world numbers one, two and three - all at the top of their games and separated by fractions of points in the rankings.

A victory on Sunday for either Singh or Els would vault them to number one providing Woods finishes outside the top two.

Just to add spice to the equation Woods and Els are in the same threeball, along with Retief Goosen, for the first two rounds.

"It's a great field," said Woods, who won the event four times in a row from 2000. "It will be just another good test. The number one ranking (is) not what drives me. It's about winning golf tournaments.

"I guess it might be more interesting for the fans, but I'm not a fan. I'm a competitor. I'm playing and my whole idea is to win a tournament. I'm going to go out there and give it my everything I've got to win this event, just like Vijay and just like Ernie and anybody else in the field."

Els is still searching for his first PGA Tour win of the season, yet the South African may be golf's form player coming off successive titles at the Qatar Masters and the Dubai Desert Classic giving him five top-six finishes in as many events.

After Padraig Harrington's spectacular victory in the Honda Classic last Sunday, Irish interest this week focuses on Darren Clarke, who will be playing with Nick Faldo and JL Lewis, and Graeme McDowell, who will have the company of Phillip Price and Charles Warren.