Fernando Alonso says the "record" levels of fuel-saving the McLaren Formula 1 drivers did in Australia shows a lack of power is not the new Honda engine's sole weakness.
Honda delivered countermeasures for pre-season reliability problems that allowed McLaren to come within six laps of getting both cars to the finish in the Australian Grand Prix, while Alonso defied pre-race expectations by making Q2 and almost scoring a point.
McLaren is braced for a much tougher outing in China, where the Shanghai circuit's long back straight is expected to punish the Honda engine's lack of performance more than in Australia.
The expectation is that planned aerodynamic upgrades will allow the team to perform relatively well in qualifying, but that the race will be a struggle.
Autosport understands the relative fuel-efficiency of the Honda package is worse than last season compared to rivals, and that Alonso was having to lift off throttle well in advance of the braking zones to save fuel in Melbourne.
"In Australia it was a record for us, the fuel saving," said Alonso, who is "definitely ready for a tough race" this weekend.
"It's going to be difficult for us this year, as long as the engine doesn't improve.
"It's not [only] power, it's many things - it's reliability, it's fuel saving, and there are a lot more implications in the driving that we cannot drive normally, because we need to drive around the engine.
"It's quite difficult, it's quite hard now, to drive the car.
"You cannot do any mistake for the whole race, because any mistake in one corner in the next straight they will overtake you with the speed difference - you need to do zero mistakes.
"I don't think we are lacking deployment, compared to the opposition, it's just we have less power, so our time on the straights is much longer than the rest."
Under the skin of Honda's latest saga
Honda is working on upgrades to its combustion engine that it hopes will be implemented by May's Spanish GP.
If the Japanese manufacturer can stabilise its new combustion process and extract more power, this should help improve efficiency by requiring the engine to burn less fuel.
Alonso's team-mate Stoffel Vandoorne also had to save fuel in Australia despite ending up two laps behind winner Sebastian Vettel at the flag - and in a race already shortened due to an extra formation lap, which gave all drivers a small fuel bonus.
"We had to do a considerable amount of fuel saving," said Vandoorne.
"I don't know exactly how much the leading teams had to fuel save. I think Melbourne was also one of the most severe tracks on the calendar.
"We'll have to wait and see how much we're going to have to do this weekend."