Fittipaldi: Piquet a challenge for Alonso

And Fittipaldi believes that Piquet Jr's extensive testing mileage for Renault this year will lead to him being a significant threat to Alonso.

"Nelsinho will be worse than Lewis Hamilton for Fernando Alonso," Fittipaldi was quoted as saying by Gazzetta dello Sport.

"Nelsinho drives excellently, he is very quick, and last year he did over 15,000km in testing with Renault. For all these reasons I think he will give Alonso more trouble than he got from the McLaren driver."

Alonso endured a difficult time at McLaren this year, having a strained relationship with team boss Ron Dennis in the wake of the management refusing to give him number one status over Hamilton.

But despite his reservations about the challenge from Piquet Jr, Fittipaldi thinks that Alonso can still be a title contender if the two-time champion helps fire up the Renault staff.

"Thanks to Fernando, [team chief Flavio] Briatore in the past had the possibility of optimising the team's performance. If he manages to do that again, the Spaniard will be able to fight for the title."