McLaren: Honda's Canadian GP failure 'absolutely not good enough'

On his return to F1 after missing Monaco to contest IndyCar's Indianapolis 500, Alonso was running 10th with three laps to go in Montreal when his engine lost oil pressure and he was forced to park.

McLaren racing director Boullier said this was one of the lowest points of an already very difficult season.

"For the first time this season, running in 10th place within spitting distance of the flag, we dared to hope," he said.

"OK, what we were daring to hope for were hardly rich pickings: a solitary world championship point for Fernando, who had driven superbly all afternoon, as he's driven superbly every race-day afternoon for the past two-and-a-half years.

"But, after so much toil and heartache, even that single point would have felt like a victory.

"And then came yet another gut-wrenching failure.

"It's difficult to find the right words to express our disappointment, our frustration and, yes, our sadness.

"So I'll say only this: it's simply, and absolutely, not good enough."

Despite running in the points, Alonso was scathing about Honda's performance, saying its straightline deficit to rival F1 teams in Canada was "dangerous".

Sunday's failure came at the end of a fractious weekend for McLaren-Honda that began with the team's executive director Zak Brown expressing "serious concerns" about Honda's F1 capability.

Honda's head of F1 Yusuke Hasegawa told Autosport the data showed Alonso had a failure of the internal combustion engine but said the root cause was unknown on Sunday night.

That was Alonso's third ICE of the season, meaning his next one will be the last he can take before incurring penalties for further changes.

"If it has damaged the MGU-H [which is Alonso's fifth], there will be [penalties]," added Hasegawa. "But we are still investigating.

"From the data point of view, it looks like the damage is the ICE.

"We're very disappointed because we lost the opportunity to get a point.

"It is positive that even though this is a power circuit, we had a chance to get a point.

"But we were disappointed we missed the chance."

Hasegawa added that it was "clear there will be more penalties" given Alonso is set to move to his fourth ICE for race eight in Baku with 12 rounds still to go.