Castroneves tops Motegi practice

However, all drivers suffered a lack of track running because of persistent rain falling on the Japanese circuit. The first practice session was cancelled altogether, and the second afternoon session was also cut short.

Castroneves emerged the fastest of the runners with a lap time of 27.193, more than 15 hundredths of a second quicker than 2004 IRL champion Tony Kanaan.

"It was a good starting session for us," Castroneves said. "We found a little difficulty in the beginning, but Ron Ruzewski, the engineer, and I were working until we found a good setup. We're very pleased with the result."

The second Penske car of Sam Hornish Jr was third quickest, but he suffered the day's only accident, spinning into the barrier between Turns 3 and 4.

"It's unfortunate the accident happened on the lap after the fast lap," Hornish Jr said. "I just turned into Turn 3 and the back end came around. I'm not sure what happened. It's unfortunate.

"It's going to be a lot of work for us over the next couple days to get back to where we need to be."

Tomas Scheckter impressed in his Vision Racing entry, with the fourth quickest time.

Pos  Driver         Chassis     Time      Laps
 1.  Castroneves    Dallara     27.1937    37
 2.  Kanaan         Dallara     27.3479    36
 3.  Hornish Jr     Dallara     27.3941    17
 4.  Scheckter      Dallara     27.4602    27
 5.  Sharp          Dallara     27.5011    24
 6.  Herta          Dallara     27.5121    20
 7.  Wheldon        Dallara     27.5243    43
 8.  Patrick        Panoz       27.5246    39
 9.  Franchitti     Dallara     27.5600    20
10.  Rice           Panoz       27.5664    27
11.  Matsuura       Dallara     27.6044    35
12.  Andretti       Dallara     27.7011    63
13.  Carpenter      Dallara     27.7068    43
14.  Simmons        Panoz       27.7103    45
15.  Dixon          Dallara     27.9393    19
16.  Meira          Dallara     28.0321    19
17.  Enge           Dallara     28.1871    35
18.  Lazier         Dallara     28.1976    37
19.  Giaffone       Dallara     28.6698    18
20.  Chesson        Dallara     28.7756    60