Sotogrande:German Martin Kaymer trailed his European Tour money-list rival Graeme McDowell by four shots as he began a challenge which could take him to the summit of world golf by the end of the weekend.
Kaymer, who needs to finish in the top two to dislodge Tiger Woods as world number one after 281 weeks, had to settle for a one-over-par 72 which included four bogeys in the Andalucia Masters first round at Valderrama in southern Spain.
On Thursday, McDowell comfortably outstripped his playing-partner and Ryder Cup team mate Kaymer with an unblemished 68 that gave the Northern Irishman an early one-shot lead over the Valderrama field.
Kaymer was, typically, neither shaken nor stirred.
"It wasn`t that bad a round and it`s not the end of the world," the 25-year-old from Duesseldorf told reporters.
"I`ve got a lot to think about -- not only being world number one but the Race to Dubai (European Money List title). So it`s important on this course not to give up. You have to stay patient and that`s what I did after making three bogeys."
Should Kaymer not finish top-two this week then Briton Lee Westwood, still nursing a sore calf muscle and resting at home, would end Woods` long reign on top of the world rankings on Sunday night.
McDowell lies second on the European Tour money-list but Kaymer leads him by more than 1 million euros ($1.39 million) and the Ulsterman knows he has to come up with something spectacular if he is to deny Kaymer that particular honour.
"I need to have some strong finishes if I`m to catch him," McDowell said. "It`s not as if I`m only 10 or 12 thousand euros behind him.
"Martin didn`t have his best day today but he`s never far from his best.
"Today I had a couple of key saves on the front nine, I think bogey-free is exceptional at Valderrama."
In 2007, Kaymer`s fine performance in finishing sixth in the Volvo Masters in his first year on tour clinched the rookie of the year award and subsequently launched his rise towards the summit of world golf.
That feat three years ago was achieved at Valderrama but on Thursday things were much bleaker for Kaymer when he ran up three successive bogeys from the 11th.
He suddenly found the sort of form that has taken him to world number three, though, smashing a huge drive on the well protected 16th, needing only a two-foot putt for his birdie to reduce the earlier damage.
If McDowell does pip Kaymer it will be his third remarkable feat of the year, alongside his maiden major title in winning the U.S. Open and clinching Europe`s nail-biting Ryder Cup victory over America earlier in the month.
His 68 earned a one-shot clubhouse lead over compatriot Gareth Maybin.