Volvo Masters 2006

An ailing Paul Casey slumped to a five-over-par 76 in the first round of the Volvo Masters on Thursday, an effort which could leave the outcome of the European order of merit in the balance.

The money-list leader needed injections to ward off nausea after suffering a stomach upset he said was the worst he had experienced when playing.

Briton Casey's only crumb of comfort was that his closest rival, second-placed Irishman Padraig Harrington, struggled to a 73 at Valderrama.

Of the four players battling to be crowned Europe's number one, Briton David Howell carded a 70 while Swede Robert Karlsson fired a 69 to move within three shots of tournament leader Jose Manuel Lara of Spain.

Casey, who leads Harrington by 147,041 pounds ($277,000) at the top of the order of merit, is unlikely to withdraw from the final event of the season.

"I'm not a fan of pulling out of tournaments and I'll try and keep going as long as I can," the 29-year-old told reporters.

"Unless a doctor says I should, I'll try and keep going as long as I can. Hopefully a good night's sleep will take care of it."

The Englishman said he would have withdrawn already if it had been any other event.

"It could be something I ate but it feels like flu because my body is aching," he said. "I had to keep resting to try to save pressure on my back.

"If it was any other tournament I probably wouldn't have teed up but the order of merit reflects a year's golf and I'm not going to let this ruin my entire year."

Howell, who said on Wednesday he only had a 50-50 chance of competing, shrugged off his troublesome right shoulder to finish four behind Lara.

The 31-year-old Englishman closed with two birdies, his effort at the 18th coming after he chipped in from 60 feet.

Harrington, who feels he needs to win to leapfrog Casey, did not get the best from a good ball-striking round.

"To try to win any tournament you probably want to play well twice and have two average days," said the Irishman. "This is one of the days I played well and I haven't scored."

Howell, who is 163,681 pounds behind Casey, was delighted with his display.

"I would have gone to the ends of the earth to play this week and I'm glad I decided to play," said Howell. "I'm certainly pleased to be tracking the leaders."

Lara followed up his third place in last week's Mallorca Classic by producing six birdies and one bogey to lead by one stroke from last week's winner Niclas Fasth of Sweden, Australian left-hander Richard Green and Briton Graeme McDowell.