Red Bull sees F1 rival Williams as a threat in the championship

The reigning champion outfit appears to have lost its status as the main challenger to Mercedes, with Valtteri Bottas having finished on the podium in the last three races.

And although crashes for Felipe Massa have harmed Williams' ability to reduce the gap to Red Bull in the constructors' title race, its pace means that the potential is there for the 67-point gap to shrink dramatically.

Red Bull team principal Christian Horner is aware that the margin between the two outfits may not have changed much in recent races, but the speed of the cars means Williams is a worry.

"They have got a quick car," he said. "We have outscored them the last couple of weekends and extended our position in the constructors' championship, but you cannot ignore them.

"They have a quick car and two quick drivers, and Bottas has been very impressive for the last few races."

Horner admitted that Red Bull was unable to race Williams in the German Grand Prix, which meant fourth place was the best it could achieve.

"I think fourth was the maximum. The two Mercedes are in a class of their own. Bottas has been hugely quick all weekend, so in reality we were racing Ferrari and the rest of the field.

"And considering the first corner where Daniel [Ricciardo] did incredibly well to avoid the accident, I thought his recovery was fantastic, and Sebastian [Vettel] got everything he wanted out of the car.

"I am sure Fernando [Alonso] felt a bit beaten up by the Red Bulls, but it was great racing. It just would be nice to be doing it nearer the front."

Despite not having been able to fight Williams recently, Horner believes that the tight and twisty layout in this weekend's Hungarian GP should suit Red Bull better.

"Hungary is a good opportunity for us, and Singapore is not too far away," he said. "So it will be interesting to see how the car performs in Hungary.

"Of course Mercedes is in a great position but hopefully we can be a little bit closer even there."