Hornish lost the lead to reigning champion Dan Wheldon with three laps to go, but grabbed back the lead a lap later and held on to the flag.

The win moved him 20 points clear of Penske team-mate Helio Castroneves, who could finish only sixth.

Brazilian Vitor Meira finished third in the race for the third year in a row.

Hornish, who won the Indianapolis 500 last month, said: "The last couple of laps were a little bit fun - but a little bit nervous, too."

Englishman Wheldon said: "We gave it everything we got. We just came up short."