If you thought that the Andretti/Unser dynasties must run out of steam some time, think again! On April 3 Marco Andretti, the 18-year-old son of Michael and grandson of Mario, made his debut in the Infiniti Pro Series, the feeder category to the IRL IndyCar Series. Also on the grid at the St Petersburg street track was 22-year-old Al Unser (son of AI Jnr and grandson of Al Snr). who has been a regular in the IPS since mid-2004. Amazingly, Andretti won on his series debut. Next stop? Indianapolis, where Marco and Al will duke it out in the Indy 500 support race.