Open runner-up Ian Poulter must rely on a wildcard pick from European captain Nick Faldo if he is to feature in the Ryder Cup.
The Englishman cannot now make the automatic selection spots after deciding to skip the Johnnie Walker Championship this weekend.
Poulter announced on Monday he is staying to compete in America even though the tournament there does not count towards the points table.
Darren Clarke, a winner in Holland on Sunday, Paul Casey and Colin Montgomerie are also looking for one of two wildcard picks, with Faldo due to announce his line-up on Sunday.
Justin Rose, Soren Hansen and Oliver Wilson, meanwhile, occupy places eight, nine and 10 on the standings, with only Martin Kaymer, Ross Fisher and Nick Dougherty able to deny them.
But Swede Robert Karlsson, who has already secured his spot, is an injury concern after being told not to risk further damage to a neck problem by practising.
Karlsson has decided not to play the Omega Masters in Switzerland (from 4-7 September) as a precaution, but hopes to play the Mercedes-Benz Championship (from 11-14 September) the week before the Ryder Cup.
The top five players from a list based on the points accrued from world rankings plus the next five best players on a European Tour-based points list make up the 10 automatic qualifiers.
European Ryder Cup team:
(as at 25/08/08. Last week's ranking in brackets)
1. (1) Padraig Harrington - Ireland - 4 caps
2. (4) Sergio Garcia - Spain - 4 caps
3. (2) Lee Westwood - England - 5 caps
4. (3) Henrik Stenson - Sweden - 1 cap
5. (5) Robert Karlsson - Sweden - 1 cap
6. (6) Miguel Angel Jimenez - Spain - 2 caps
7. (7) Graeme McDowell - Northern Ireland - 0 caps
8. (8) Justin Rose - England - 0 caps
9. (10) Soren Hansen - Denmark - 0 caps
10. (9) Oliver Wilson - England - 0 caps
The top eight automatic American qualifiers secured their places after the USPGA on 10 August. Captain Paul Azinger will name his four wildcards on Tuesday 2 September.
The 37th Ryder Cup will take place at Valhalla Golf Club in Louisville, Kentucky, USA, from 19-21 September.