Felipe Massa has questioned the credibility of both Robert Kubica and Paul di Resta as potential Williams drivers for the 2018 Formula 1 season.
The Grove team is still considering its options for next year, with tech chief Paddy Lowe insisting that Massa is still a candidate, alongside Kubica, di Resta and Mercedes-backed Pascal Wehrlein.
Kubica has tested for Williams twice - at Silverstone and the Hungaroring - as the team evaluated his performance following the accident that put an end to his F1 career in 2011.
However, Massa believes that it is inevitable that the Pole will be hampered by physical issues.
"I have no idea how he's driving, first of all," he said in an exclusive interview with Motorsport.com's GP Gazette.
"To be honest, I cannot do what he's doing, driving with only one hand.
"It's impossible for me to believe that he will not suffer with some of the races with this car that we're driving that is a lot more difficult physically.
"I really respect what he's doing, it's just amazing. But it's impossible to believe that he will not have some issues."
Massa also reckons di Resta would not be a good choice for the team, adding that the Scotsman's recent record in the DTM has not been convincing.
Di Resta has finished 15th, eighth, fifth and 11th in the four DTM seasons he has contested since losing his Force India F1 drive at the end of 2013 - winning two races.
"I don't believe he's the right driver for the team, to develop the car and show the results and everything," Massa said.
"Plus I don't think he's doing a great job in what he's racing as well. Anyway, I'm not here to complain about anything, that's only my opinion."
Massa acknowledged that there is nothing more he can do to influence the team's decision.
"I'm quite confident that people know what is the best for the team," he said. "This is pretty much what people know.
"As I said, sometimes in F1 it's not only your talent that counts, sometimes you have some other things around, and this is unfortunately part of F1 for some of the teams."
Massa, who returned to Williams this year after having announced his retirement in 2016, says he is prepared for 2017 to be his last season.
"I'm good on that, I have zero frustration," he said. "As I've said before, I did a lot more than I expected.
"So if it needs to finish, it's the time. If it doesn't need to finish, it's because maybe something is still reserved.
"As I said, I'm quite relaxed, thinking about my job, thinking about my car. The time for being frustrated is passed already in my career."