Lee Westwood is back into the world number four spot he last occupied eight years ago - and has become Europe's highest-ranked player once again.

An eighth-place finish in the WGC-HSBC Champions tournament in Shanghai moved Westwood above Paul Casey, whose rib muscle injury flared up again and forced his retirement on the final day.

Casey has returned to America to see a specialist. He has pulled out of this week's Hong Kong Open and is doubtful for next week's Dubai World Championship, where a victory could give him the European Tour money list title for the first time.

Even though Ian Poulter was only 45th in China, he improves two spots to a career-high 13th, but Ross Fisher drops two to 19th despite finishing 28th.

That is because Ernie Els and Rory McIlroy were second and fourth respectively and, as a result, climb to 16th and 17th.

Latest leading positions on the world rankings:

1 Tiger Woods 15.70pts, 2 Phil Mickelson 9.22, 3 Steve Stricker 7.38, 4 Lee Westwood 6.13, 5 Paul Casey 6.02, 6 Padraig Harrington 5.71, 7 Henrik Stenson 5.63, 8 Kenny Perry 5.36, 9 Sergio Garcia 5.31, 10 Jim Furyk 5.23

11 Martin Kaymer 5.11, 12 Geoff Ogilvy 4.82, 13 Ian Poulter 4.71, 14 Stewart Cink 4.62, 15 Sean O'Hair 4.60, 16 Ernie Els 4.47, 17 Rory McIlroy 4.37, 18 Lucas Glover 4.20, 19 Ross Fisher 4.18, 20 Retief Goosen 4.09

Other leading Europeans:

27 Luke Donald, 28 Robert Karlsson, 32 Soren Kjeldsen, 37 Oliver Wilson, 41 Soren Hansen, 43 Miguel Angel Jimenez, 44 Francesco Molinari, 45 Alvaro Quiros, 47 Anders Hansen, 48 Simon Dyson, 51 Graeme McDowell, 53 Peter Hanson, 54 Gonzalo Fernandez-Castano, 65 Justin Rose, 66 Alexander Noren, 70 Chris Wood, 81 Anthony Wall, 85 Edoardo Molinari, 95 Thomas Levet, 96 Nick Dougherty