BERLIN (AFP) - Four-time Formula One world champion Sebastian Vettel predicts a debacle for Red Bull unless they improve their car before the season opens at the Australian Grand Prix in two weeks.

"First of all, just getting to the finish would be a success," the German told broadcaster Servus TV. "If half the drivers fail to finish, then maybe we could take a few points."

The 26-year-old is bidding for a fifth consecutive world title when the season kicks off in Melbourne on March 16, but endured a frustrating four-days of testing the new Red Bull car in Bahrain, which concluded on Sunday.

His mentor and Red Bull's advisor Helmut Marko echoed Vettel's concerns.

"We are not where we want to be," said the Austrian after the second testing session of the winter. "The start of the season has come at least two months too early for us.

"It will be difficult to catch up, we don't know when or if that is possible."

Vettel failed to complete a single lap in testing on Saturday due to electrical issues and problems with the car's Renault engine.

Williams' Felipe Massa posted the fastest time in Bahrain, clocking 1min 33.258secs, closely followed by Mercedes' Lewis Hamilton, who was just 0.06 seconds, while Vettel came in 18th fastest overall with team-mate Daniel Ricciardo in 10th.

Vettel finished Sunday's final testing ninth fastest, 4.190 secs slower than Hamilton's best, after suffering a spin after a brakes failure, but still managed to completed 77 laps, his highest mileage of the winter on a single day.