Mercedes' motorsport boss Toto Wolff has apologised on behalf of the entire team to Lewis Hamilton after he suffered a second retirement of the season.

Hamilton again finds himself playing catch up in the race for this year's Formula One world championship after failing to score in the Canadian Grand Prix on Sunday, with team-mate Nico Rosberg finishing second.

Although both cars suffered a loss of one of the energy recovery systems - the MGU-K - Hamilton was forced to retire after 47 laps as a consequence of the failure of his rear brakes.

Gallingly for Hamilton, title rival Rosberg managed to work through the difficulties posed by the loss of power and brakes.

Although at one stage with a train of three cars behind him as they had closed down the gap to the leader, only Daniel Ricciardo in his Red Bull found a way past to claim his maiden victory.

With a 22-point cushion now to Rosberg, Hamilton is adamant he can again claw back the deficit, as he did when he trailed the German by 25 points following the season-opening race in Australia.

For his part, Wolff felt particularly bad for Hamilton post-race as he said: "First of all, we have talked and we are just sorry to have let Lewis down.

"It is a shame, particularly with the championship as close as it is, but he is in good spirits and he is a fighter and I have no doubt he will come back.

"As for Nico, he deserved to take those points because he had a car that was heavily handicapped against all the others."

Rosberg's stunning reliability record of two wins and five seconds from the seven grands prix to date naturally makes it very tough for Hamilton to continue to play the hunter.

It could yet be the much-maligned double-points system for the final race will be crucial for the 29-year-old Briton.

Attempting to find the positives for Hamilton from a bad situation, Wolff said: "How many races are we into the season? Seven. So we have another 13 to go effectively as we have double points last race."

Suggested to Wolff that scenario could save Hamilton's campaign, he replied: "It could, but we have to be careful about talking of an easy home run now."

Wary of the threat slowly coming from Red Bull following Ricciardo's win, with reigning four-times champion Sebastian Vettel third, Wolff reined in thoughts of a walk in the park to claim both titles.

Although still 119 points ahead of the Red Bull in the constructors' championship, and with Ricciardo 61 adrift of Rosberg, Wolff added: "Red Bull scored massive points and can close that gap pretty quickly.

"I guess it will come down to an end of season (showdown) with double points."

Initially, Wolff has to first investigate the cause of the failure of the MGU-K, with the anomaly being it occurred on both cars at almost exactly the same time in the race.

"They were racing at exactly the same pace and had exactly the same temperatures," said Wolff.

"In that particular part of the MGU-K we saw temperatures which were higher than expected.

"We were unaware they could have such a detrimental effect. The MGU-K just shut down and we could not reset it.

"We told both drivers to manage the brakes, to be careful, because when you lose the electric motor and you lose the electric braking it leads to the brakes overheating massively.

"Both complied exactly to what they were told, although it was very marginal, so when Lewis entered in to the pits, and with his car stationary, the temperatures rose.

"When he went out again the pedal went soft. Nico was lucky not to have that.

"It is just another part which we have to analyse and understand as I guess this can happen. The consequence was obviously detrimental to the whole car, the brakes, and in particular to Lewis."