Umbrellas were as plentiful as on a wet day at the races. But the difference for the opening round of the $1.5 million World Cup here at the Mines Resort was that their function had to do with sun rather than rain. And it was almost unbearably hot.

So, Ireland's Paul McGinley (70) and Padraig Harrington (71) had reason to be well pleased with an opening aggregate of 141 - one under par. It left them in a share of fifth place, six strokes behind leaders Japan but, in generally moderate scoring, only a stroke behind the favourites from the United States.

Stifling humidity, prompting competitors to drink up to nine litres of water for the round, took its toll on most of the them, especially when allied to wickedly difficult greens. Notable exceptions were Japan's Mamoru Osanai, who had a sparkling 65, and Tiger Woods, whose 67 included a stunning back nine of 30.

Further down the individual order, Philip Price of Wales shared third place with a 68; Colin Montgomerie joined McGinley in a share of 10th place and England's Mark James and Peter Baker were among those in a tie with Harrington for 15th.

By his own estimation, Woods had experienced conditions worse than these only once before in his career. "When I played in Bangkok in 1997, the temperature was 104 degrees," he said. "The real problem out there today was that there was hardly a breath of wind to cool us down."

Interestingly, Woods and Osanai birdied the same five holes on the back nine, though the American also birdied the 12th. As it happened, 29-year-old debutant from Tokyo started his round at the 10th, which he birdied, and went on to card four-in-a-row from the 15th to the 18th.

By comparison, his play of the outward journey was decidedly sloppy, with birdies at the third, fifth and sixth behind partially offset by bogeys at the fourth and ninth. Still, with his equally obscure partner, Mitsuo Harada, doing his bit with a one-under 70, they swept into a four-stroke lead by the end of the day.

Close observers of recent Japanese form in this event, however, will note their early dominance with some scepticism. For instance, they also led with opening round scores of 64 and 70 in New Zealand last year, only to slip back to an eventual share of 11th place. The Americans can be expected to have better staying power, though Mark O'Meara seemed thoroughly dispirited by a 74. "Basically I'm not a happy camper," he admitted. "This is the way it's been all year. The problem is that I'm not getting my approach shots close enough to the pin."

Woods characterised his own effort as a Dr Jeckyll and Mr Hyde performance in that a double-bogey six at the ninth left him two over par at the turn. The problem there stemmed from a blocked second shot into trees from where he pitched to 18 feet above the hole and then three-putted.

But the familiar sparkle returned on the homeward journey, where putts of 10 feet and 15 feet found the target for birdies at the 10th and 12th. Then came four-in-a-row from the 15th, largely through the formidable combination of prodigious driving and precise iron play.

A case in point was the 329-yard 15th, where his drive finished pin-high on the left from where he chipped to two feet. And he went on to reduce the 523-yard 17th to a drive, five iron and two putts from 40 feet.

His only complaint afterwards was the injudicious use of cameras by enthusiastic locals. "But it wasn't as bad as Taiwan last week when it seemed like everybody in the gallery had a camera," he said with a wry smile.

McGinley has got used in recent months to achieving a paltry reward with the blade. So, a round which contained two birdies and a lone bogey, had much to do with admirably precise striking from tee to green. In fact from the fifth onwards, he hit every green in regulation.

He bogeyed the short, 170-yard second where a six-iron tee-shot finished in a hazard but responded immediately by sinking a 20-footer for a birdie at the next. Then came 13 straight pars until a three-wood approach set up a two-putt birdie at the 17th. "I'm trying to be patient but I need to convert more of my chances into birdies if we're to win," he said afterwards.

Harrington was coasting along at level par until he three-putted the 12th from 25 feet for a bogey. So he was understandably pleased to recover with birdies at the 16th (20-foot putt) and 17th, where he had an eagle putt of 15 feet. But his spirits were crushed at the final hole.

Misjudging a seven-iron second shot to a pin cut tight into the back left of the green, he overshot the target, chipped back to six feet and missed the par putt. "After missing a lot of putts out there, that was a very disappointing finish," he said.

Finally, those who have been following the fortunes of impoverished Jamaican Ralph Campbell will note that he shot a 74. What may have escaped them, however, is that he did it in a new pair of golf shoes, given to him as a gift by the local club professional.

The World Cup is to become one of the new World Championship events. A joint announcement will be made today by the International Golf Association, custodians and organisers of the World Cup, and the International Golf Federation.