Robert Kubica's recovery from horrific rally crash injuries might not take as long as a year.

The 12 month prediction was made by the surgeon in charge of the Polish driver's nearly eight hour operation on Sunday, but Renault team boss Eric Boullier said on Monday that doctors' forecasts are always conservative.

"With yesterday's (Monday's) news and the medical bulletins, I was worried," Flavio Briatore, who visited the 26-year-old in hospital, told the ANSA news agency.

"I was prepared for the worst. But when I saw him we even shared a joke and he asked about my son.

"I called Alonso and Bernie and told them I think they will see him on the track before the end of the season.

"He's a great and tough guy and I am sure he will come back soon," added the Italian.

"Considering the terrible accident he suffered, he's ok.

"We didn't talk about the accident but about Formula One and about a quick return. Considering his will and his fitness, I would bet he will come back within five or six months," said Briatore.

Kubica's friends Fernando Alonso, Vitantonio Liuzzi and Pastor Maldonado have also visited the hospital.

"He didn't tell me anything special," new Williams driver Maldonado told 422race.com, "(except) that he's quite well."

La Gazzetta dello Sport tracked down for comment Alessandro Nannini, who was driving for Benetton in 1990 when his right arm was severed in a helicopter crash.

The Italian did not return to F1 but he subsequently raced touring and sports cars.

"His injury is different to the one I had," the 51-year-old said. "His arm was not completed separated, and the nerves, tendons and muscles will grow back in just a matter of time.

"For sure Robert will come back to racing," added Nannini.

Kubica's hand surgeon Igor Rossello is also confident, but he warned that it is "impossible" to make precise predictions.

"With the nervous system, you never know, but if Alessandro Nannini managed to go back, why shouldn't Kubica?" he said.