Dixon moves ahead in final practice

Thick fog forced the split sessions to start half an hour behind schedule, but once the first group of cars hit the track, Penske driver Castroneves was dominant, heading second placed Dan Wheldon (Ganassi) by nearly a full second.

Dixon was in the second group, and initially struggled to match Castroneves' earlier time - lapping 0.4 seconds slower than his title rival in his first runs and brushing the wall as he attempted to improve.

But in the closing moments Dixon, who can clinch the 2008 title this weekend, found the speed he had been lacking and beat Castroneves by 0.1222 seconds, with third placed Ryan Hunter-Reay 0.7 seconds adrift in his Rahal-Letterman Racing car.

Will Power (KV) and EJ Viso (HVM) completed the top five, despite the latter briefly halting the session when he spun down the Turn 3 escape road. Wheldon was classified sixth on combined times.

Having been drafted in late last night to replace the injured Enrique Bernoldi at Conquest, Alex Tagliani was allowed to participate in the full hour to give him a chance to acclimatise to the IRL Dallara-Honda for the first time. The Champ Car veteran built up speed steadily, despite a quick spin at Turn 8, and ended the morning in 22nd.

After his series of spins yesterday, Marty Roth was in the wars again as he crashed his Roth Racing Dallara before he could even set a time, causing an almost immediate stoppage at the start of the session.

Dale Coyne Racing's Mario Moraes was also in trouble, being sidelined early on with broken front suspension.

Pos  Driver             Team                 Time
 1.  Scott Dixon        Ganassi              1:12.5015
 2.  Helio Castroneves  Penske               1:12.6237  + 0.1222
 3.  Ryan Hunter-Reay   Rahal Letterman      1:13.2561  + 0.7546
 4.  Will Power         KV                   1:13.3127  + 0.8112
 5.  EJ Viso            HVM                  1:13.5223  + 1.0208
 6.  Dan Wheldon        Ganassi              1:13.5671  + 1.0656
 7.  Oriol Servia       KV                   1:13.6896  + 1.1881
 8.  Bruno Junqueira    Dale Coyne           1:13.7408  + 1.2393
 9.  Justin Wilson      Newman/Haas/Lanigan  1:13.7484  + 1.2469
10.  Tony Kanaan        Andretti Green       1:13.8790  + 1.3775
11.  Danica Patrick     Andretti Green       1:13.9315  + 1.4300
12.  Vitor Meira        Panther              1:13.9654  + 1.4639
13.  Ryan Briscoe       Penske               1:14.0342  + 1.5327
14.  Graham Rahal       Newman/Haas/Lanigan  1:14.2029  + 1.7014
15.  Hideki Mutoh       Andretti Green       1:14.3779  + 1.8764
16.  Marco Andretti     Andretti Green       1:14.5639  + 2.0624
17.  Tomas Scheckter    Luczo Dragon         1:14.6665  + 2.1650
18.  Darren Manning     Foyt                 1:14.6864  + 2.1849
19.  AJ Foyt IV         Vision               1:14.9097  + 2.4082
20.  Ed Carpenter       Vision               1:15.5961  + 3.0946
21.  Buddy Rice         Dreyer & Reinbold    1:15.6014  + 3.0999
22.  Alex Tagliani      Conquest             1:16.4424  + 3.9409
23.  Jaime Camara       Conquest             1:17.0898  + 4.5883
24.  Milka Duno         Dreyer & Reinbold    1:19.0112  + 6.5097
25.  Mario Moraes       Dale Coyne           1:23.6836  + 11.1821
26.  Marty Roth         Roth