Alex Albon predicts a chaotic Saturday at the Canadian GP, with rain forecast to fall throughout.
The Williams driver is debuting an upgrade package on his FW45 this weekend and hopes it will see him rejoin the midfield fight.
However, an unusual Friday compromised the team's run programme and left Albon uncertain about how much of a difference it will make.
Officials opted to extend Free Practice 2 by 30 minutes as a result, though a dirty track, two red flags, and rain complicated the session.
“It's hard to say, really,” Albon said when asked for his feeling about the upgrades.
“Obviously, FP1 was pretty compromised, and then FP2, we got decent running in.
“We didn't really get a proper short run programme in, we did a long run, and actually that was really positive, so we've definitely made an improvement.
“Hard to know, quantify, where that puts us in terms of pace, but it's all going in the right direction.”
That picture is unlikely to get any cleared for Williams on Saturday, with the rain that hit the circuit late in Free Practice 2 expected to remain.
Running in Free Practice 3 is therefore likely to be limited as it will add little value to teams while introducing significant risk given the proximity of the walls.
“It's going to be a bit chaotic,” Albon suggested of Saturday's running.
“Obviously, I caught the end of that FP2 session and it rains pretty hard here, so I wonder if there are going to be a few more delays coming tomorrow.
“But it's all to play for.
“I feel like these conditions create a bit of the unknown; got to be on the track at the right time.
“It even dries up pretty quick here, considering how warm it is for the rest of the day when it's not raining, so let's see.”