Searing temperatures are expected over Budapest, with the early race-day forecast predicting 36°C, the kind of conditions Lewis Hamilton and Nico Rosberg have struggled to overcome while driving for the German marque this season.
Mercedes has been susceptible to a high rate of tyre degradation when the track is hot.
That could undermine their impressive qualifying form as, between them, Hamilton and Rosberg have taken six of the past seven pole positions.
Add in the fact Mercedes was banned from last week's young-driver test at Silverstone, where Pirelli's new range of tyres were analysed by the other 10 teams, and the team heads to the Hungaroring struggling to catch up.
Following a number of high-speed blowouts during the British Grand Prix, Pirelli was forced to revise its rubber. That means last season's construction is now married to this year's compounds.
Mercedes conducted a private test with Pirelli at Barcelona in May, and that led to the team being banned from the young-driver test. The only information they have from the event is data given to them by the tyre-maker.
The goal remains to go into the summer break on a high. Mercedes is second in the constructors' championship, with two race wins.
"The final race before the summer break is always a milestone for the team and an opportunity to review our performance before our staff enjoy a well-deserved break during the summer shutdown," Brawn said.
"However, the season has not been without its challenges and we have had some very tough races. This happens over the course of a season and you have to take the highs and lows and find your path to making improvements.
"Both Nico and Lewis have visited the factory in the two weeks since we returned from Germany, and everyone has been working very hard to investigate our tyre sensitivities ahead of the elevated temperatures we will undoubtedly experience this weekend in Budapest."
The Briton said the team must get maximum results from the two 90-minute practice sessions tomorrow, ahead of qualifying on Saturday and the race on Sunday.
"Friday will also be our first opportunity to work with the new tyres on our car, so we have a great deal to learn in a short space of time," he said.
For Hamilton, the fact he has failed to yet win for Mercedes in his debut campaign, while Rosberg has taken the chequered flag twice, is irksome. The Englishman has a superb record in Hungary, winning on three occasions in his six years in F1, including dominating last year's race with McLaren-Mercedes.
"It is an important weekend for us, and we need to get off to a good start on Friday when we have the chance to try the new tyres for the first time," Hamilton said.
"I know everyone is working really hard to improve our overall performance and to address the issues we experienced at the last race."
Following Sunday's race, the F1 teams have a three-week break ahead of the Belgium Grand Prix on August 28, the first of seven races in a 10-week span leading up to the November 3 Abu Dhabi Grand Prix.
Follow us @SprtNationalUAE