Williams's pitstop frustration rising

Williams has encountered numerous difficulties with its pitstops this season, the most high-profile being during the Belgian Grand Prix when a medium tyre was incorrectly fitted to the right-rear wheel of Valtteri Bottas's car among a set of softs.

Head of vehicle performance Smedley has conceded the team was again slow with its stops in Japan, where Bottas lost fourth place to Kimi Raikkonen's Ferrari in the final pit sequence.

"We're making some inroads," said Smedley, with regard to the pitstop situation.

"We had slow pitstops for other reasons [in Japan] and part of that definitely helped Kimi to get in front of Valtteri as well.

"We probably just weren't quick enough to react to get that final set of tyres on and keep him behind. Very disappointing.

"It is something we need to address. We can't just erase it like that. It is something we do need to improve.

"We have a fairly regular occurrence of one issue, which is the wheel nuts have been a little bit tight to take off.

"But then in Japan we had other things which were thrown at us as well.

"So as usual, there's a tsunami of work to do after every race, it's just this has been a slightly bigger tsunami."

The only saving grace for Smedley was Bottas at least took 10 points at Suzuka, while nearest constructors' championship rival Red Bull suffered on that circuit, failing to score at all.

It means with five rounds of the championship to run, starting with the Russian Grand Prix on October 11, Williams has a 69-point cushion over Red Bull in the battle for third.

"From a race like that, it [outscoring Red Bull] was definitely the primary thing we needed to try and do, so I was quite happy we managed to gain 10 points on them," said Smedley.

"It was a positive, but not enough of a positive - they didn't score anything - and it was a race where we should have had maybe 18 or 20 points on them, not just 10."