Team boss Toto Wolff admits that Mercedes' rivals are fast closing in on the championship leaders, and that the squad will need to find new ways to maintain its edge in the sport.
Wolff said that recent gains in performance from Red Bull's new partnership with Honda, together with Ferrari's straight line speed advantage, are putting the Silver Arrows under more pressure than ever before.
“It shows us that we have got to reinvent ourselves in a way and I see this as a really positive challenge," the Austrian said before the summer break in a report from Crash.net's Luke Smith.
This season Mercedes gambled on focussing on downforce and cornering speeds to counter the Ferrari challenge.
But he admitted that he hadn't been expecting such a revitalised challenge from Red Bull so soon after their switch of engine providers.
“The Red Bull chassis was always among the best and it still is,” he said. “And then Honda has made a big step forward from last year to this year, and all credit to them.
“I am happy to see that for Formula 1 because a strong Honda is good for Formula 1 and good for the competition," he insisted.
"If there is a fourth power unit supplier that has a competitive edge then there is generally positives for all of us.
Being beaten to pole at Hungary by Red Bull's Max Verstappen was a big shock for the team. Driver Valtteri Bottas said that it would motivate Mercedes to redouble their efforts, and Wolff agreed with him.
“I think he’s damn right," he said, adding that five consecutive constructors champions from 2014 was no guarantee of another in 2019.
“We had a good streak of success and it feels now that probably the push that we need to do is even bigger," he acknowledged.
“The others are catching up, and it’s easier to catch up than to maintain the level and set the benchmark
"There is a reason why nobody has ever won six consecutive constructors and drivers championships, because it is not easy.
“I guess we all know that," he said. "But we have got to push harder and smarter in order to stay ahead."
Despite the mounting pressure on them, Mercedes hold a 150 point lead over Ferrari in the team standings after 12 of 21 races in 2019. Red Bull are a further 44 points behind.
And in the driver battle, Lewis Hamilton's eight wins so far this season mean that he's well out in front with 62 points in hand over his team mate.
But Bottas has just seven points more than Max Verstappen, who has moved into third place in the championship ahead of Ferrari duo Sebastian Vettel and Charles Leclerc.
Wolff refused to rule out a move for Verstappen when the Dutch driver becomes a free agent at the end of 2020. But he did say there was no chance of the team offering Fernando Alonso a race seat.
"Fernando is undoubtedly one of the strongest drivers," he told Italy's La Gazzetta dello Sport. "
[But] due to a series of circumstances the top teams already have their 'alpha' driver," he explained, which in Mercedes' case is currently Lewis Hamilton.
"We don’t want to repeat certain stories from when the two were together with McLaren," said Wolff.