Red Bull fear struggles
Red Bull's problems are so severe one of the team's top brass has suggested they may never catch their rivals this season.
The Milton Keynes-based marque emerged from pre-season testing with a dire reliability record as they encountered a series of issues.
Reigning four-times champion Sebastian Vettel completed just over 850 kilometres, almost 2,000kms behind Mercedes' Nico Rosberg.
Only four drivers finished below the 26-year-old German on the mileage charts - and one of those was team-mate Daniel Ricciardo. Lotus duo Pastor Maldonado and Romain Grosjean and Marussia's Max Chilton were the others.
The concerns are such within the team that at this stage it appears highly unlikely either Vettel or Ricciardo will the see the chequered flag at the season-opening Australian Grand Prix on March 16.
That has led to Red Bull advisor Helmut Marko, right-hand man to billionaire owner Dietrich Mateschitz, questioning the team's prospects for the forthcoming campaign.
On the 'Sport und Talk' programme 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."
Highlighting some of the difficulties the team are facing, 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 (power-unit supplier) Renault on the test benches day and night to improve the situation for Melbourne."