World champions Red Bull have endured such a torrid time that one of the team's senior advisers fears they will not catch their rivals all season.
In a withering assessment of the team's prospects for 2014, Helmut Marko, right-hand man to billionaire owner Dietrich Mateschitz, also said the season-opening race in Melbourne comes "two months" too soon for Red Bull.
They suffered so many problems in the 12 days of winter testing that it appears unlikely Sebastian Vettel or Daniel Ricciardo will finish in Australia on March 16.
The furthest they managed consecutively was just 20 laps, and reigning champion Vettel completed just over 850 kilometres, almost 2010 behind Mercedes' Nico Rosberg.
On the Sport und Talk program on Red Bull's in-house Servus TV network, Marko said: "The opening race comes at least two months too early for us. This is a very serious matter. At the moment we do not know in what time frame it will be possible to catch up, or if it is possible at all."
Marko, who has previously warned the team's engine supplier Renault to "get a grip", said Red Bull were working "day and night" with the French manufacturer ahead of the first race.
Highlighting some of the troubles the team are facing with the new, more complicated hybrid engines, Marko added: "We are struggling with turbo lag. You step on the gas, but the power does not arrive. It comes all of a sudden, the wheels spin, the car slides and you lose speed. We are working with Renault on day and night to improve the situation for Melbourne."
On pre-season form, Vettel's chances of a fifth consecutive world championship appear to be slim, as on one day of the final test in Bahrain he did not manage to complete a single lap. Only four other drivers - one of whom was his team-mate Ricciardo - finished below the 26-year-old in the mileage charts across three pre-season tests.
"First of all, just getting to the finish would be a success," Vettel said. "If half the drivers fail to finish, then maybe we could take a few points."
On Sunday in Bahrain, Vettel also admitted that in addition to Red Bull's reliability problems the team are not quick enough. "We cannot do the times that the guys at the top are doing for a couple of reasons, but at the moment we have bigger problems to solve than just the pace."
The Telegraph, London