The two contenders for the IndyCar Series title, leader Scott Dixon and runner-up Helio Castroneves started right away to battle it out on the Belle Isle circuit during the first two practice sessions today.

Ganassi driver Dixon, who leads Castroneves by 43 points, was the fastest in the morning's session on a still-dirty track and he led by a comfortable half a second over Penske's Castroneves.

But in the improved conditions of the afternoon, the Brazilian took his turn at the top of the charts with the fastest time of the day, more than half a second in front of Dixon.

Panther Racing's Vitor Meira was third in second practice just in front of Ryan Briscoe who is also competing in the ALMS event.

Graham Rahal of Newman-Haas-Lanigan was the best of the ex-Champ Car pilots with a seventh place. Young Marco Andretti didn't seem to be on the right track with the 20th spot.

Practice one:

Pos Driver Team Time
1. Scott Dixon Ganassi 1:13.9714
2. Helio Castroneves Penske 1:14.4954 + 0.5240
3. Ryan Briscoe Penske 1:14.9002 + 0.9288
4. Tony Kanaan Andretti Green 1:15.6494 + 1.6780
5. Ryan Hunter-Reay Rahal Letterman 1:15.7004 + 1.7290
6. Danica Patrick Andretti Green 1:15.7323 + 1.7609
7. Graham Rahal Newman Haas Lanigan 1:15.9390 + 1.9676
8. Dan Wheldon Ganassi 1:15.9760 + 2.0046
9. Darren Manning Foyt 1:16.0432 + 2.0718
10. Vitor Meira Panther 1:16.0602 + 2.0888
11. Ernesto Viso HVM 1:16.2482 + 2.2768
12. Hideki Mutoh Andretti Green 1:16.4874 + 2.5160
13. AJ Foyt IV Vision 1:16.7216 + 2.7502
14. Will Power KV 1:16.7979 + 2.8265
15. Tomas Scheckter Luczo Dragon 1:16.8601 + 2.8887
16. Bruno Junqueira Dale Coyne 1:16.9212 + 2.9498
17. Oriol Servia KV 1:17.2074 + 3.2360
18. Mario Moraes Dale Coyne 1:17.3831 + 3.4117
19. Buddy Rice Dreyer & Reinbold 1:17.4258 + 3.4544
20. Marco Andretti Andretti Green 1:17.6144 + 3.6430
21. Justin Wilson Newman Haas Lanigan 1:17.9563 + 3.9849
22. Ed Carpenter Vision 1:18.3216 + 4.3502
23. Jaime Camara Conquest 1:19.4043 + 5.4329
24. Enrique Bernoldi Conquest 1:19.4495 + 5.4781
25. Milka Duno Dreyer & Reinbold 1:23.5300 + 9.5586
26. Marty Roth Roth 1:33.5782 + 19.6068

Practice two:

Pos Driver Team Time
1. Helio Castroneves Penske 1:13.2059
2. Scott Dixon Ganassi 1:13.6996 + 0.4937
3. Vitor Meira Panther 1:13.9816 + 0.7757
4. Ryan Briscoe Penske 1:14.1373 + 0.9314
5. Danica Patrick Andretti Green 1:14.4452 + 1.2393
6. Tony Kanaan Andretti Green 1:14.6517 + 1.4458
7. Ryan Hunter-Reay Rahal Letterman 1:14.6552 + 1.4493
8. Darren Manning Foyt 1:14.7119 + 1.5060
9. Oriol Servia KV 1:14.7147 + 1.5088
10. Bruno Junqueira Dale Coyne 1:14.7326 + 1.5267
11. Will Power KV 1:14.8398 + 1.6339
12. Tomas Scheckter Luczo Dragon 1:14.8960 + 1.6901
13. Justin Wilson Newman/Haas/Lanigan 1:14.9100 + 1.7041
14. Graham Rahal Newman/Haas/Lanigan 1:14.9609 + 1.7550
15. EJ Viso HVM 1:15.0732 + 1.8673
16. Dan Wheldon Ganassi 1:15.2644 + 2.0585
17. Hideki Mutoh Andretti Green 1:15.5606 + 2.3547
18. Marco Andretti Andretti Green 1:15.5702 + 2.3643
19. Ed Carpenter Vision 1:16.2213 + 3.0154
20. Mario Moraes Dale Coyne 1:16.4200 + 3.2141
21. Buddy Rice Dreyer & Reinbold 1:16.6437 + 3.4378
22. AJ Foyt IV Vision 1:16.7840 + 3.5781
23. Jaime Camara Conquest 1:17.2781 + 4.0722
24. Enrique Bernoldi Conquest 1:18.0948 + 4.8889
25. Milka Duno Dreyer & Reinbold 1:20.6361 + 7.4302
26. Marty Roth Roth 1:25.0063 + 11.8004