Mercedes boss Toto Wolff believes that McLaren and Renault could pose a serious threat to the four-time world championship squad in 2018.
That's in addition to the team's usual rivals, Ferrari and Red Bull.
"This is the pinnacle of motor racing you need to respect every team and the top drivers," Wolff told Motorsport.com.
"We are taking Ferrari, we are taking Red Bull, we are taking McLaren, we are taking Renault seriously.
"These guys can fight for a championship," he insisted. "And some others might be surprising us."
Wolff said that while he expected competition from all of these teams, he still felt Mercedes would be able to rise to the challenge.
""I want to remain humble," he said. "[But] if we are able to align the dots like we have done in the last year, then we will be winning races. And then we will be fighting for championships.
"If we don't, then we haven't been good enough," he said succinctly.
Ferrari's flying start to the 2017 season had been a sharp reminder to Wolff never to take anything for granted in F1.
The Scuderia won the Australian Grand Prix last year. And Sebastian Vettel was ahead of Lewis Hamilton in the drivers standings after Monaco.
"How the [SF70H] performed on track was exceptional," recalled Wolff. "The step they made over the winter was probably the biggest step of all the teams.
"Ferrari could have won more races," Wolff conceded. "We're taking them very seriously as a real contender [this year] - like we do with the other teams.
Mercedes had to work hard on improving their own car and overcoming its "diva" characteristics. But they pulled if off, while Ferrari stumbled with reliability issues.
"I am happy that we kept it together," Wolff acknowledged. "We have a record of 11 race victories versus the five of Ferrari. And the stopwatch never lies."
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