Ferrari may have topped Friday's practice in Montreal but Fernando Alonso says they are still in the dark about their true performance.
The Spaniard came to the fore in Friday's second practice at the Circuit Gilles Villeneuve, posting a 1:14.818 on the supersoft Pirellis.
That was good enough to put Alonso at the top of the timesheets, although only just as Lewis Hamilton was a mere 0.012s adrift.
But rather than be excited about his pace, Alonso revealed that Ferrari were not able to test all their updates given the morning's wet track.
And as such, he has yet to discover Ferrari's true potential in Canada.
"It was an untypical Friday, affected by the extremely changeable weather," said the double World Champion.
"We didn't manage to complete our programme because the track was wet in the morning and so only tomorrow will we find out if the updates we tested here produce a real performance evolution.
"It was very important that we try them just as it was also important to try the new Pirelli tyres.
"Felipe and I made different choices for the long runs and this is another reason why we will have to wait for the outcome of qualifying to understand more."
Alonso is keen to close the gap on Sebastian Vettel come Sunday's grand prix as he trails the reigning World Champ by 29 points in the race for this year's title.
He does, however, concede that it won't be an easy weekend to do that.
"The only certainty is that we must ensure we make the right decisions, because today we saw how getting a clean lap depends a lot on the time you make the decision and what track conditions are like at that moment.
"We can expect a very complicated weekend, because the weather is due to remain changeable right up to Sunday and judging the grip level will be difficult, both in qualifying and in the race."