If they're in pursuit of the Tiger, then he's not ready, just yet, to rest on his laurels and let them catch him. In fact, Tiger Woods, the world number one, is continuing his efforts to hit the ball longer and straighter than ever before by playing prototype drivers in the big-money, end-of-season events that dominate the run-up to Christmas.

This week, at the exclusive Sherwood Country Club in southern California, Woods is the host in the Target World Challenge which is confined to 16 invited guests. The winner will receive $1 million, and the last - 16th - placed player will get $130,000. Woods is defending the title, while Ernie Els, Sergio Garcia and David Duval turned down the opportunity to play.

Woods, though, will be using yet another prototype driver, designed by Nike, during the tournament, all part of his long and intricate campaign to find the driver he wants to play. It is estimated that, in the 10 months since the AT&T Pebble Beach tournament, Woods has used over 170 drivers. He has even tried one with a graphite shaft but, in last weekend's skins match, where Mark O'Meara was the big winner, he reverted to his familiar steel shaft and length of 43 ½ inches.

"We're pretty close to getting the driver I want," said Woods. "I might be hitting the ball just a little too high now, but I thoroughly enjoy being able to work the ball again, left to right and right to left, so maybe I need one with a ball flight just a touch flatter."

So the process continues, trying to match Woods with his driver, a multi-million-dollar project for fledgling golf club manufacturer Nike, which has made Woods the linchpin of its campaign to sell clubs. Woods ranked sixth in driving distance on the US Tour in 2002, averaging 293.3 yards, and he was 11th in total driving, a combination of distance and accuracy.

According to Tom Stites, lead engineer at Nike, Woods complicates the project because he likes to hit so many different shots with his driver. "He's just one of those guys, like Arnold Palmer or Jack Nicklaus, who's never going to be satisfied."

Most players hit the ball further last year, mainly because of improvements in equipment. Like everyone else, Woods wants distance and is able to achieve as much as anyone else with the speed of his swing and his ability. But he has high demands for his equipment as well.

A deep-faced driver with a large clubhead that still conforms to USGA rules provides several places to launch the ball to fly further. At the same time, Woods is also a control player, using spin to help him hit a draw or fade. Tests have shown a club with a slightly smaller head can increase spin.

The problem is finding the right combination. But Stites knows he's on the right track when he hears Woods make contact with the ball. "It's like a Stradivarius," he said. "Put it in some people's hands, it sounds like a different instrument."

Tests have also shown Woods could average an additional eight yards in distance with every half-inch increase in the length of the shaft of his club, but Stites says Woods is comfortable at 43½ inches, one and a half inches shorter than the US Tour average.

So, Woods will get to use another prototype driver in this week's World Challenge where Padraig Harrington is the only Irish player in the select field. He appears by virtue of his world number eight ranking and is joined by Woods, Phil Mickelson, Retief Goosen, David Toms, Davis Love, Vijay Singh, Jim Furyk, Nick Price, Michael Campbell, Chris Di Marco, Bob Estes, Rich Beem, Colin Montgomerie, Mark O'Meara and Bernhard Langer.

Harrington, incidentally, moves on to Mexico next week for the World Cup of Golf - where he will partner Paul McGinley - before taking a nine week break.

Elsewhere, Irish players Tim Rice, Ciarán McMonagle, Gavin McNeill and Padraig Dooley compete in the South African Players' Championship at Royal Cape on the Sunshine Tour this week.

An elbow problem has forced Nick Faldo to withdraw from the England team for next week's WGC - EMC² World Cup at Vista Vallarta, Puerto Vallarta, Mexico.

Paul Casey will now partner Justin Rose in the event.