Lewis Hamilton has admitted McLaren are struggling to resolve a number of issues that have left him questioning his Formula One world title hopes this season.
Hamilton and McLaren endured another relatively unproductive day in testing yesterday as hopes for a full-race simulation were wrecked by hydraulics and exhaust issues.
It resulted in Hamilton completing just 57 laps in fits and starts, ultimately finishing fourth quickest and a second down on reigning world champion Sebastian Vettel in his Red Bull.
These are currently proving to be troublesome times for McLaren who have just two days of testing remaining before the F1 circus heads to Australia for the season-opening grand prix on March 27.
Asked if he was concerned about his apparent lack of preparation, Hamilton told Press Association Sport: "I'm not worried.
"For me, I've been racing a while, so if there was a race tomorrow I could get in the car and do that, no problem. I can do qualifying, no problem; can do practice, no problem.
"But in terms of how long the car can go in terms of reliability and our true pace, that's an unknown factor for us because in the time we have had we've not been able to maximise things.
"That's no-one's fault, just issues you have in testing, and this is what testing is all about, finding where your weaknesses are so you can build on them and fix them.
"We've been focusing on those, but we definitely have several issues that are not as easy to rectify as we had hoped."
It leaves McLaren already playing catch up with the likes of Red Bull and Ferrari, with Hamilton conceding the car is currently not good enough for him to win the title.
"I have every belief in my heart that I can win many, many more world championships," added the 2008 champion.
"But do I believe I have a car to win the world championship at the moment? I don't.
"That doesn't mean it won't become a world championship winning car.
"There were improvements, which is at least a positive. It's not all negative.
"So as long as we keep pushing in the right direction, and with the new things we have coming several races down the line, hopefully they will enable us to close the gap and compete for wins.
"As long as we pick up a good few points in the first few races, then we won't be miles behind.
"Say for example we were able to be in the top five for the first three or four races, get those points, and then if we happen to have a car capable of winning, then it would still be possible.
"So I'm definitely not shutting the year off. Everything is still to play for."