The 39-year-old driver from Mexico City, who owns his own racing team, had a previous best finish of fifth in the IndyCar Series, at Texas on 12 June.

Fernandez just edged out Rice, a three-time series winner this year.

England's Dan Wheldon was third, with Kosuke Matsuura and series points leader Tony Kanaan fourth and five.

Belterra Casino Indy results:

1. Adrian Fernandez (MEX) G/H, 200 laps in 1hr 38min 20sec
2. Buddy Rice (USA) G/H, at 0.0581 sec
3. Dan Wheldon (GBR), D/H, 200 laps completed
4. Kosuke Matsuura (JPN) G/H, 200
5. Tony Kanaan (BRA), D/H, 200
6. Dario Franchitti (GBR), D/H, 200
7. Vitor Meira (BRA), G/H, 200
8. Ed Carpenter (USA), D/C, 200
9. Bryan Herta (USA), D/H, 200
10. Darren Manning (GBR), G/T, 200