Robert Kubica insisted that the six points scored in Canada were his toughest of the season after the Renault driver picked up a seventh place finish in Montreal.
Kubica, winner the last time F1 raced in 2008, qualified eighth on the grid on the prime tyres but suffered tyre degradation that forced him into an early pitstop.
The Pole then battled on – and off – track with Michael Schumacher for position and almost collided with Adrian Sutil on pit entry, an incident that saw him reprimanded by stewards after the race.
Having elected to run the option tyre for his final stint, Kubica started to close in rapidly on Mercedes driver Nico Rosberg but ran out of laps to try and make a move for sixth place on a challenging day of racing.
“The six points I got this afternoon were my toughest points of the year,” he said. “We chose to qualify on the prime tyre yesterday and hoped it would be an advantage in the first part of the race, but unfortunately it didn't work out. I had a lot of rear degradation in the first stint, which meant I pitted early, then the rear tyres went off in the second stint as well.
“At the end of the race, I did a short stint on the option tyre and I was pushing to close down the gap to Rosberg, but I ran out of laps even though I was catching him quickly. It was a tough race for me but I think we must be optimistic for Valencia. The circuit should suit our car, and we will have more new developments to help us improve our basic pace.”