Hamilton saw his 14-point championship lead wiped out after a dominant Sebastian Vettel marched to victory at the Circuit Gilles Villeneuve.
Indeed Vettel now leads Hamilton by one point after the British driver was left to rue a Mercedes engine problem as he finished an underwhelming fifth.
Mercedes chief Toto Wolff claims the team that makes the fewest mistakes will win the title
Unlike all their rivals, Mercedes failed to bring a planned engine upgrade to Montreal – and it would cost Hamilton dearly.
The Briton, running on a seven-race-old engine, reported he was down on power in the opening exchanges, and had to pit earlier than planned as his Mercedes team made changes to his overheating machinery.
Hamilton, fourth at the time, headed into the pit lane on lap 16 of this 70-lap race, but the early stop allowed Daniel Ricciardo to usurp the Mercedes car.
Mercedes have dominated the sport since 2014, but the fiercer competition provided by both Ferrari and Red Bull this year has led to a series of errors.
Lewis Hamilton struggled on his way to a fifth place finish at the Canadian Grand Prix
A timing glitch during a virtual safety car period cost Hamilton the win in Australia before a gearbox issue resulted in a grid drop for the Briton at the next round in Bahrain.
Mercedes can also be accused of playing it safe when they did not bring Hamilton in for new tyres following a late safety car in China.
And here, their failure to give Hamilton a fresh engine has contributed to him losing the championship lead.
Hamilton was relieved to finish the race following power problems during the race
‘This is a major wake-up call for every single member of the team,’ Mercedes boss Wolff said. ‘I’m the opposite of confident moving forward.
‘Everybody needs to assess how to improve our performance.
‘This year’s championship is going to be decided by the one who makes the least mistakes. This is the new reality.
Sebastian Vettel now leads the world championship by one point following victory
‘It is a three-way team fight and six cars can win races. We cannot take anything for granted and think it is going to be a walk in the park.’
|1. Sebastian Vettel||Ferrari||3||121|
|2. Lewis Hamilton||Mercedes||2||120|
|3. Valtteri Bottas||Mercedes||2||86|
|4. Daniel Ricciardo||Red Bull||0||84|
|5. Kimi Raikkonen||Ferrari||0||68|
|6. Max Verstappen||Red Bull||0||50|
Hamilton added: ‘I could have lost a lot more points here. I am super-grateful I finished. I was down on power, and every single lap I was on edge waiting for the power to drop away.
‘We have got to keep working, and keep pushing because Ferrari will falter if we can apply the pressure.’
Vettel claimed the Scuderia’s first victory in Canada since Michael Schumacher triumphed here 14 years ago, and his first win in five races.
His success was never in doubt after he surged off the starting line and controlled the race – despite the chequered flag accidentally being waved one lap early by Canadian model Winnie Harlow – to apply the championship pressure back on to Hamilton.