Golf:Singapore's weather could have a big part to play in whether Rory McIlroy clinches the European Tour money list title this weekend. The world number one was restricted to just eight holes on the first day of the Singapore Open, a thunderstorm suspending play in mid-afternoon with him level par and five behind leader Thomas Bjorn.

Last year’s tournament was cut to three rounds because of torrential rain and the shorter the event the harder it will be for McIlroy to climb from his current 38th position into the top three he needs for the Order of Merit crown. Already the PGA Tour’s leading money-winner this season, the 23-year-old is trying to achieve what was an unprecedented double until Luke Donald did it last season.

Even missing the halfway cut at Sentosa would still leave him a massive favourite, however. None of his main challengers is in the field, nor will they be in Hong Kong when he defends the title there next week and after that there is only the DP World Tour Championship in Dubai to come.

McIlroy controversially skipped last week’s world championship in China to watch girlfriend Caroline Wozniacki play tennis in Bulgaria, but the roles are reversed now. After an opening bogey she saw him hit back with birdies on the fourth and fifth, but then came another dropped stroke at the short eighth just before the sirens sounded because of the approaching dark clouds.

Wozniacki’s fellow Dane Bjorn had long finished his day’s work by then, a five under par 66 putting him one in front of England’s Simon Khan, Spaniard Pablo Martin and Thai Chinnarat Phadungsil.

Former world number three Paul Casey, back to form after crashing out of the game’s top 100 following his snowboarding accident last Christmas, is only two behind, but three-time winner Adam Scott is alongside McIlroy after a 71, Phil Mickelson was two worse than that and Padraig Harrington ran up a seven in his 74.

Now 41, players’ committee chairman Bjorn won three times last season, but has gone 14 months without tasting more success. He birdied three of his last six holes in the oppressive morning heat and humidity and said: “We get quite used to it, but you’ve just got to pace yourself a little bit and not use too much energy.

“It’s quite nice for the body to be feeling warm and nice out there — no cold for the old joints to get you into trouble!”

Five years ago Martin became the first amateur to win on the European Tour and he has triumphed twice more since then, but at 166th on the money list he needs a top eight finish to save himself from a return to the qualifying school.

“I haven’t been able to put together four decent rounds in a row, but hopefully my luck will turn,” said Martin, who also has the Hong Kong Open to fight for his future. After two months out with a dislocated shoulder Casey made only one halfway cut from March to mid-August, but his last three finishes have been third, fifth and sixth.

“The golf has been really nice lately and I’d love to sneak a win in before my season finishes,” he commented. “It’s the first time I’ve played in this kind of humidity in a long time. Just hanging on to the club with sweaty hands is the biggest problem.”