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.
Read the full article on eurosport.co.uk: Alonso: Power not Honda's only problem