BMW Sauber boss Mario Theissen is adamant his team will bounce back despite making their worst start to a Formula One season.

Now in their fourth year, Sunday's Bahrain Grand Prix was also the team's most abject performance yet as Robert Kubica and Nick Heidfeld were lapped, finishing a miserable 18th and 19th.

"The team has to show - and will show - how competitive we are," said Theissen. "Everyone has to deal with this from time to time and I'm confident we will bounce back."

When you consider Kubica gave the team their maiden pole in the same race last year, with the duo finishing third and fourth, Sunday's result underlines the wrong turns made by BMW Sauber with regard to the new rules.

Another reason for the malaise stems from the fact it was decided early on to plough resources into a significant upgrade due to be unveiled for the Spanish Grand Prix in Barcelona on May 10, rather than try to keep pace with their rivals at the flyaway races.

With just four points on the board from Heidfeld's second place in the rain-shortened race in Malaysia, Theissen is hoping - perhaps now praying - such plans reap rewards.

"We decided before the start of the season on a big development package for Barcelona, and I can only hope this will pay off," said Theissen.

"Today, it looks like we are behind, but if the package is good the picture can change within two weeks.

"What we have seen now is quite surprising, with new regulations it's a close field. In Bahrain, we saw a third different team completely dominate qualifying, which is unusual.

"That shows, together with small gaps, it can change again within a few races."