Toto Wolff says Mercedes is set to bring an aero upgrade for its car in time for the British Grand Prix as it begins to feel increasing pressure from improving rivals Red Bull and Ferrari.

Though Mercedes has won all but one race this season, its margin over its main competitors has noticeably shrunk in recent events, with both Red Bull and Ferrari leading in Monaco and Canada initially only to be out-foxed strategically and lose out to Lewis Hamilton each time.

With Ferrari seemingly spurred on by an engine upgrade ahead of the Canadian Grand Prix, with Vettel qualifying less than two tenths off pole, the performance of the SF16-T in race conditions has also caught the eye of Wolff as the series heads to Azerbaijan this week for the first time.

"Interestingly Red Bull's performance in qualifying was better than in the race performance, and Ferrari was strong in qualifying and in the race.

"If you see the long-term development slope of Ferrari is that they are getting better every race and they have had some bad luck at the beginning of the season. But this weekend again you could see that the Ferrari is capable of winning races."

As a result, Wolff says Mercedes is working hard to maintain its dwindling advantage, with constant progress on the power unit and an upgrade being readied for round ten at Silverstone.

"We will push hard," he continued. "We will have an aero upgrade probably ready for the British Grand Prix and on engine-wise everybody is really working hard in order to bring performance. It's necessary."

This week's European Grand Prix in Azerbaijan is the first to be held on the streets of Baku.