Fernando Alonso concedes it is difficult to say whether or not Robert Kubica will make a return to Formula One.
Former BMW and Renault driver Kubica has been out of action since the start of last season after he suffered life-threatening injuries during a rallying accident in Italy in February 2011.
Although the Pole is determined to return to competitive racing - he has already done a series of tests in an F1 car simulator - his close friend Alonso admits he is unsure if the 27-year-old will ever make a comeback.
"It's very hard to say whether Robert will return to 100 percent fitness and be able to race again in Formula 1," he said in an interview for September's F1 Racing.
"Now and again we speak and I know how much it hurts him to be so far away from what has always been his world. He has to keep calm and think first and foremost about recovering total functionality of his body, then he can think again about racing."