Niki Lauda says "the alarm bells are ringing" at Mercedes having been so closely challenged by Williams in the Austrian Grand Prix.

Felipe Massa and Valtteri Bottas locked out the front row for Williams, with the two drivers leading the first stint before Nico Rosberg and Lewis Hamilton hit the front. While Mercedes went on to take a one-two, Bottas was just eight seconds behind in third place and Lauda said it was clear to him that Mercedes' advantage was being reduced.

"The alarm bells are ringing that the competition is coming closer," Lauda said. "If the alarm bell rings in time then you can do something. If you sit back - which we don't try to do - you miss out. So what we are going to do is keep on developing the car."

While Lauda concedes that the gap between Hamilton and Rosberg is getting substantial and hopes the two are able to fight only between themselves in Silverstone.

"It is [big], no question, because the Montreal race was a disaster for [Hamilton]. But he will keep on fighting, don't worry. He will be more motivated now going to Silverstone after this result and the points difference. So I really look forward to a good Silverstone race between the two.

"I hope that nobody else comes in between [them]. This we have to avoid and keep pushing the team - Paddy [Lowe] and Toto [Wolff] - to go forward again."