Amid Sauber's obvious financial troubles, Brazilian Nasr claims that his personal performance struggle so far in 2016 is due to a problem with his chassis.
"I am 100% sure the car is not right," he is quoted as saying by Brazil's UOL after the Chinese Grand Prix.
"I'm struggling all the time but [Ericsson]'s happy with the car from the start. I drove that car in Barcelona and I was happy too," Nasr added.
Swede Ericsson told UOL that he would be happy to swap cars at Sochi in order to confirm or rule out Nasr's suspicions.
"Why not? I'm willing," he said. "I wouldn't mind. I will make this proposal and see what he says."
Ericsson suspects that he is simply out-performing Nasr on merit.
"I was already stronger at the end of last year," he said. "I have worked very hard in the preseason to be even stronger this year and I have confidence in the team and the car.
"I think I have clearly shown who is the strongest driver."
The Russian Grand Prix takes place on May 1.