Jenson Button and Lewis Hamilton may have clambered out of undamaged cars on Friday in Montreal, but they still suffered from the consequences of other drivers ploughing into the walls of the Circuit Gilles Villeneuve.

"It's very difficult to make any setup changes when there are so many red flags," said Jenson Button after sitting out three interruptions to the two practice sessions. "It's surprising how many of them there were today."

He was only too aware, however, that Canada is a tricky venue. If a driver catches the kerb the wrong way, he hits the wall.

"Hopefully, tomorrow will be an accident-free day," added the Englishman.

His team-mate Lewis Hamilton took a similar view and expressed sympathy for his less fortunate colleagues: "That's racing. People test their cars to the limit, and they would be told off if they didn't. There is no room for error in a place like this, and unfortunately some people have now paid the price for it. But they'll be back again tomorrow."

Hamilton was also slightly unlucky in that he suffered a puncture when Jerome D'Ambrosio crashed to bring out the last red flag of the day.

"It must have been debris, because I had only just gone out on track," the Briton said.

Despite the interruptions though, McLaren managed to put some valuable work in. Hamilton reported that the team had evaluated various new parts, though he also felt that he still wasn't getting the perfect balance.

"Our pace on the long runs is pretty good – the pace is certainly there. Once again, it's looking very close between Red Bull, Ferrari and us. So we'll be working on qualifying and getting the car set up properly. Then it's a matter of keeping our fingers crossed."

Button said that McLaren had decided not to go for fast laps and low-fuel runs on Friday but rather to focus on how well the supersoft tyres performed with a full tank – a much more important consideration from his point of view. He believed that they would be able to tune the car for use with a reduced fuel load on Saturday.

Apart from which, he drew the same conclusions as Hamilton: "The Red Bulls are fast, Ferrari likewise, Mercedes and us too – I think it will be somewhat closer than it has been in the last few races."