Red Bull motorsport boss Helmut Marko says the amicable relationship between Max Verstappen and Lewis Hamilton may have been undone for good as a result of the pair's clash last month at Silverstone.
While not close friends, Verstappen and Hamilton previously enjoyed a respectful and friendly rapport off the track.
But the Dutchman was heavily critical of his arch-rival and of Mercedes after the British Grand Prix, blaming Hamilton for his high-speed crash and denouncing team and driver for celebrating their win while the Red Bull driver was in hospital undergoing medical checks.
The clash in Great Britain and another Mercedes-induced setback suffered by Red Bull and Verstappen in Hungary dropped the 23-year-old back down to second in the title fight, 8 points behind Hamilton.
The fierce battle will resume next week at Spa-Francorchamps, but Marko hopes both drivers will keep their rivalry "under control".
"We want to win the world title and for that you have to score as many points as possible," Marko told Motorsport Magazin.
"Max knows that, Hamilton knows that too. But something happened that cannot be undone so quickly in the relationship between these two, if it happens at all.
"But I hope both of them can keep it fair and under control."
Circumstances allowed Hamilton to outscore Verstappen by 40 points in the last two races. But the Red Bull driver's tally of five wins this season clearly demonstrated his strength as a title contender in 2021.
"I think Max has proved this season that he is really at World Championship level," added the Austrian. "In Bahrain, of course, we had some problems with track limits, which cost us the win, pole and fastest lap.
"The sledgehammer blow in Baku, when he was leading masterfully and lost his victory because of that blowout, that’s a shame.
"But his whole attitude and relaxed way of approaching racing shows he has taken another step towards the top."
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