MotoGP stars Valentino Rossi and Marc Marquez will be following Fernando Alonso's upcoming Indy 500 debut with great interest and have tipped the Spaniard to be "really fast" in the iconic oval race.
Alonso is missing the Monaco Grand Prix to drive at the Indianapolis Motor Speedway on May 28 in a McLaren entry powered by Honda and run by Andretti Autosport. The Spaniard will race with just two weeks' worth of practice and a private test at IMS on May 3, taking place between the F1 races in Russia and Spain, to his name.
Seven-time MotoGP champion Rossi -- who tested a NASCAR stock-car at the Charlotte Motor Speedway in 2013 -- thinks Alonso has a big challenge ahead of him. .
"It was a surprise, because it's strange that Alonso won't race in Monaco," Rossi said. "But I think the situation with the car [in F1] is difficult and he wants to try something else.
"It will be very interesting to understand the potential of Alonso at Indy because it's completely another world, especially when you race on the oval. The one time I went [on an oval] with NASCAR and it was very interesting, but you understand it's very different. It will be a great challenge and very interesting to see."
Marc Marquez, who has won three of the last four MotoGP titles, backs his fellow Spaniard to be very competitive at the event.
"The decision on my side is difficult to understand because Monaco is one of the good tracks that maybe with McLaren he can get a good result," Marquez said. "It is a race that's difficult to understand from outside.
"You must be really lucky, slipstream is very strange, but the talent of Alonso, all of the drivers in Formula One say is one of the best ones in a car. His talent is there, I think he'll be really fast."