While rival four-time champion German Sebastian Vettel and Ferrari rejoiced in their first Montreal win since 2004, which ended Hamilton and Mercedes' three-year supremacy at the Circuit Gilles Villeneuve, the defending champion Briton was hit by engine problem and finished fifth.
"Straight from the start, the power started dropping out," said Hamilton, whose Mercedes engine was in its seventh race this season, while other teams introduced new upgraded power units.
"There were lots of hesitations, engine dropping in power, so I thought the engine was going to blow. We don't have a problem with cooling, we just had something fail that sent temperatures up.
"It was an unforeseen issue and that was losing us power. We were operating far below our power target.
"The whole race, 70 laps, I thought the engine was going to blow up. It's gone a long way this season.
"I was conflicted at the end, because I wanted to push to get that next position, but if the engine goes in the last couple of laps...the second to last lap I had some big dips in power...it was like 'please', just one more lap!" He added that he felt that his fifth position might be critical in the title fight by the end of the year and he believed that Ferrari would yet be fallible under pressure.
"I am still here to win and I still believe we can win," he said, shrugging off the engine-cooling problems that required an early pit-stop and ruined his race.
"I have complete confidence in my guys and I am putting my energy into it. We have potential in this car and there is a long way to go." Mercedes expect to introduce their upgraded second engine at the French Grand Prix later this month.
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