MotoGP star Valentino Rossi, once on the verge of a switch to F1 following a series of promising tests for Ferrari, has now closed the door on four-wheel grand prix racing.
"I'm done with F1 unfortunately," Italy's Sky Sports
quotes Rossi as saying. "I'm too old, the train has passed. But I'll be cheering for Ferrari, Alonso and Raikkonen."
Rossi tested Ferrari F1 cars off-and-on between 2004 and 2010.
The 34-year-old is returning to Yamaha in MotoGP this year, after suffering two winless seasons at Ducati.
John Surtees is the only person to have won world championships in both two and four-wheeled grand prix racing.