Mercedes Formula 1 boss Toto Wolff says Max Verstappen must be considered a title threat after the Red Bull driver followed up his two recent wins with pole in Hungary.
There are 10 rounds of the 2019 season remaining, and Verstappen is 63 points adrift of points leader Lewis Hamilton, and just 22 behind Valtteri Bottas's second place.
Verstappen has finished in the top five in every race of 2019 so far and has outscored the two Mercedes drivers over the last four races.
When asked if Verstappen was a title threat, Wolff replied: "Yes - there are 10 more races to go, so 260 points to score. What's our advantage? 60-odd.
"You can see from the sheer maths that Max is somebody we need to take seriously and consider as a title rival in the same way we need to consider the two Ferrari drivers as title rivals.
"We cannot afford to take the foot off the throttle."
After being beaten to pole at the Hungaroring by Verstappen, Bottas said that Red Bull and Honda's recent surge will only encourage Mercedes to work harder.
"Obviously it always depends on the tracks and circumstances," he said.
"But if you look at the trend, let's say from the last five races, Red Bull has been the one improving the most - closing the gap and today qualifying on pole.
"So, for sure they are doing many things right, and that means we have to work harder as a team. But I'm sure Ferrari isn't standing still either."
Wolff echoed his driver's sentiments when asked about Bottas's comments by Autosport.
"I think he's damn right," he said. "We had a good streak of success, and it feels now that the push that we probably need to do is even more [necessary].
"The others are catching up, and it's easier to catch up than to maintain the level and set the benchmark.
"There's a reason why no one ever won six consecutive drivers' and constructors' championships, because it is not easy.
"I guess we all know that, but we've got to push harder and smarter in order to stay ahead."