As anyone who has ripped up an old betting docket is only too aware, not every wager pays off.

So it was with Padraig Harrington who gambled that adding the Mallorca Classic on to his schedule would boost his chances of winning the European Tour's Order of Merit title, only to miss the cut - for just the third time on tour this season - and consequently head on to this week's season-ending Volvo Masters in exactly the same position as he was before making the addition to his itinerary.

Harrington may have failed to leapfrog money leader Paul Casey, but at least the Dubliner still has a chance - albeit an outside one - he is 11 to 2 to with Paddy Power bookmakers as against Casey at 1 to 7 to win the Order of Merit - should he finally manage to this week conquer Valderrama, a course that has not always suited his eye in previous visits down the years. His best finish in the event on the course is tied-19th, last year and in 2004.

In what has turned out to be one of the more exciting races for the Harry Vardon trophy, awarded annually to the European Tour's top money winner, four players have a mathematical chance of claiming the title: Casey, who is in pole position; Harrington, who is the main chaser, some €218,185 behind; David Howell, the long-time leader who had led from last November's Champions tournament in China until the World Matchplay in September, and Robert Karlsson, seeking to become the first Swedish winner.

Casey has had two weeks off, at his home in Arizona, preparing for the Volvo Masters which has a top prize of €666,660 and a second prize of €444,440. Such large amounts offer those players in pursuit sufficient incentive in what is a limited field confined to the top-60 players on the Order of Merit after last week's Mallorca Classic.

In actual fact, the field is smaller - with just 54 players after the decisions of Ernie Els, Retief Goosen, Nick O'Hern, Michael Campbell, Vijay Singh and Darren Clarke - not to play. Clarke, incidentally, is the only one of Europe's Ryder Cup winning team to miss out on the Volvo Masters, a decision taken so that he can spend more time with his sons, Tyrone and Conor. The Ulsterman plans on playing only two more events this year, the defence of his Taiheiyo Masters in Japan in two weeks and Tiger Woods's Target World Challenge in December.

While Casey heads into this week's final counting event on the European Tour in the lead, he has admitted to feeling somewhat fortunate to be in the position. Howell had been the long-time leader until Casey overhauled his compatriot by winning the World Matchplay.

Howell, troubled by an assortment of injuries, has had only one top-10 finish (in the BMW International in Munich in September) since he won the BMW Championship at Wentworth back in May. Howell, like Casey, has not played since the Dunhill Links.

"I feel very lucky to be ahead of "Howler", claimed Casey. "David's had injury and fitness problems for much of the year and, if he hadn't, I think he would have been so far ahead by now that it would all be over. Having said that, I feel very, very honoured to be at the top of the list right now. It would be wonderful to win the Order of Merit. I think I would have to pinch myself if I won. To be number one in Europe at the end of the year is a heck of an achievement for anybody."

It was Harrington's win in the Dunhill Links that propelled him into contention for the Order of Merit title, and he has used the quest for the Harry Vardon trophy as motivation since the Ryder Cup. "It would be a big deal to me to win the Order of Merit. The Order of Merit being such a big deal - certainly something you want to have in your CV - and that keeps you pushing on."

Harrington is one of four Irish players in the 54-man field at Valderrama. Paul McGinley, who showed good form over the weekend in the Mallorca Classic to secure just his second top-10 finish since the European Open in July, is the defending champion, while Damien McGrane and Graeme McDowell are also in the field.

McGinley had gone to Mallorca knowing that his place in the Volvo Masters was secure, despite the fact he was outside the top 60 on the money list at the time. "The new rule allowing the defending champion to defend his title worked very much to my benefit, but I wanted to qualify as of right by doing well in Mallorca," he said.

At least McGinley heads to Valderrama knowing there are signs his form has finally turned around, and he admitted: "Getting to Valderrama will bring back the happy memories for sure."