Kimi Raikkonen admitted Lotus was struggling to get the Pirelli tyres in the right operating window during Canadian Grand Prix free practice on Friday.
Several teams had difficult getting the tyres to perform in the cold conditions, and Raikkonen fears a poor qualifying performance if the situation does not improve for Saturday.
"Obviously the lap time was not the fastest but it's very close here between everybody so if you go faster you can gain a lot of places," said Raikkonen after ending the day back in 11th.
"The car is not too bad but we have some issue with getting the tyres working.
"If we can get the tyres to switch on it makes a much bigger difference than any small set-up thing.
"It's the same story as in Monaco. We were pretty OK but we were not fast enough in qualifying because of the tyres not working.
"If we can get the tyres working, it makes a massive difference."
He does not think there is anything else wrong with the car beyond the difficulty with tyres.
It's not too bad but the feeling is that if we can switch the tyres on it will go better," Raikkonen said.