Marco Andretti, the 21-year-old US grandson of auto racing legend Mario Andretti, set the fastest practice lap on Tuesday on the first day of open practice for the 92nd Indianapolis 500.

Andretti turned the quick lap around the 2.5-mile (4km) Indianapolis Motor Speedway oval at 226.599 mph (362.558 k/hr) to lead 33 cars that turned 1,385 total laps in the six-hour session ahead of Saturday's pole qualifying.

Andretti, the 2006 Indy 500 runner-up to Sam Hornish, will try to erase a legacy of heartache at Indy for his family. Father Michael never won at the "Brickyard" and Mario captured only the 1969 crown in decades of effort.

Brazilian Tony Kanaan, Andretti's teammate for Andretti-Green Racing, was second at 225.269 mph, New Zealand's Scott Dixon third at 225.011, Australian Ryan Briscoe fourth at 224.804 and England's Dan Wheldon fifth on 224.727mph.

The session marked the first time since 1995 that all US open-wheel series elite racers had been together at Indy. A split into Champ-car and the Indy Racing League came in 1996 and ended only with a merger this year.

Two weekends of qualifying will fill the 33-car field for the 25 May race.

The past two Indy 500 winners will not take part this year, with Hornish and 2007 winner Dario Franchitti of Scotland now racing in the US stock car series

AFP