Honda Formula 1 boss Yusuke Hasegawa says he is “ashamed” by the grid penalty Fernando Alonso has incurred for the manufacturer’s home race in Japan.

Alonso had qualified his McLaren inside the top 10 but will start rear of grid due to a 35-position penalty picked up before Saturday’s final practice session.

Honda found a hydraulic leak in the Spaniard’s engine after Friday practice and chose to replace the power unit altogether rather than try to fix it.

Team-mate Stoffel Vandoorne will start ninth, and a grid penalty for Ferrari’s Kimi Raikkonen means both McLaren-Hondas could have started the Japanese Grand Prix in points contention but for Alonso’s setback.

“I’m very ashamed,” Hasegawa told reporters after the session.

“We didn’t have an engine failure, we had some hydraulic leakage, which we can change if we find out (the cause) with enough time, but we couldn’t, that’s why we need to change the engine.”

McLaren-Honda had to break curfew regulations for the second time this season to complete the engine change, which racing director Eric Boullier said was “frustrating for everybody” and “does affect the preparation for the weekend in terms of pitstops and practices, so it’s not ideal”.

Alonso now faces an uphill battle to recover a decent result in the last Japanese GP before the current McLaren-Honda alliance is dissolved at the end of the season.

“With all the high-speed corners it will be difficult to follow the [other] cars and will be a tough race,” Alonso said.

“Hopefully we can do a good start and play a good strategy and we’ll see how the pace is.

“We need some speed to overtake cars on the straights, which normally we don’t have, so it’s going to be (a) demanding, complex race to execute.

“There are not really any clear targets. Hopefully close to the points will be good.”

Race start this afternoon is 1600 AEDT.

Starting grid: Japanese Grand Prix