Frentzen says Bridgestone should be worried

Ralf Schumacher's Williams scored Michelin's first Grand Prix win at San Marino last weekend in only the fourth race since the French company returned to Formula 1.

As the threat from Michelin increases, Frentzen believes that Jordan and other Bridgestone-shod teams could end up suffering as the Japanese firm struggles to meet the needs of the top two.

"Bridgestone should be nervous," said Frentzen, "and I think they should be worried about Michelin. I think they're finding it difficult to find a tyre that suits both of the top teams [McLaren and Ferrari]."

Bridgestone is set to introduce a new tyre format for next weekend's Spanish Grand Prix which includes a softer rear compound and a wider front tyre. Teams tried the new rubber at Silverstone on Thursday with the McLarens of Mika Hakkinen and David Coulthard topping the times.

Frentzen was less impressed with the new format and although he did not run with the wider front tyres due a lack of time, the softer rear rubber did not suit the German's Jordan-Honda.

Bridgestone still has the overall upper hand and has dominated the top positions in both qualifying and races this year. However, the Japanese firm could be compromised by supplying both Ferrari and McLaren, while Michelin can concentrate on its sole front-running team, Willliams by supplying tyres best suited to the Grove-based team.

Despite finishing in sixth and seventh place on the final day of Silverstone testing this week, Schumacher Jr and team mate Juan Pablo Montoya were the fastest Michelin runners by almost half a second.

Bridgestone is expected to make its new tyre configuration available in Barcelona, depending on feedback from Ferrari, which has also been carrying out evaluation work this week at Mugello.