Honda chief Yusuke Hasegawa has said he is worried McLaren will be left behind this season due to other teams making big gains with their power units.
McLaren finished rock-bottom of the standings in terms of distance covered at the Circuit de Catalunya, racing through at least seven different power units and suffering four breakdowns in the final two days of testing.
Yet Hasegawa ultimately believes it is the improvements made by other teams that has seen McLaren struggle so much and not primarily because of Honda's reliability.
Asked whether he envisaged McLaren having such a disastrous winter, Hasegawa said that all the issues faced had come as a bit of a surprise.
"Of course not," Hasegawa told Racer.com.
"Of course we knew the performance level but we didn't know the level of the other teams, so from a comparison point of view we are a little bit scared of the situation and it's too optimistic for us to expect a very good result in Melbourne.
"But from a trouble point of view, of course I didn't expect such a wide variety of problems that we suffered.
"Everything that has happened has not been seen on the dyno, I believe. Especially the day two issue and this week's day one issue, we didn't expect such a problem."
"Of course we also improved our engine performance level; however, it looks like the PU performance improvement of the others is better and higher than us. We may even be further back, so that is very disappointing.
"From the settings or a setting point of view we may have some things we can do in these two weeks. In the next two weeks we will try to find some ways of tuning the engine, and it can have better performance [by Melbourne], definitely."