Padraig Harrington could be battling four rivals for the Order of Merit title in next week’s Volvo Masters

Trailing Robert Karlsson by €297,425, the Dubliner must finish first or second at Valderrama and hope that the Swede finishes outside the top five.

But Harrington could also be fighting off challenges from Lee Westwood, Miguel Angel Jimenez and Henrik Stenson.

Karlsson is in the driving seat after following back-to-back wins with a third place finish at the Portugal Masters on Sunday.

But he is not playing in this week’s Castellon Masters in Spain and so the issue will not be decided until the season-ending Volvo Masters at Valderrama starting on Thursday week.

If Harrington wins there Karlsson will have to finish second to take the money list title - and if Harrington is second Karlsson needs to be fifth or better.

If Westwood wins, Harrington is out of the running and Karlsson will require second or third place. But if Jimenez wins, Harrington must finish second and Karlsson will have to finish 39th or worse.

Stenson is the only one of the quintet playing in Castellon and if he wins the final two events, Harrington must finish second at Valderrama and Karlsson no worse than seventh to deny him.

Order of Merit race

1 Robert KARLSSON  €2,695,248
2 Padraig HARRINGTON €2,397,823 (€297,425 behind Karlsson)
3 Lee WESTWOOD €2,228,642  (€466,606 behind Karlsson)
4 Miguel Angel JIMÉNEZ €2,018,596 (€676 652 behind Karlsson)
5 Henrik STENSON €1,773,617 (€921,631 behind Karlsson)

This week - Castello Masters, winner’s share €333,330

Next week - Volvo Masters, winner’s share €708,000, 2nd €472,000, 3rd €266,000, 4th €212,000, 5th €180,000.