Nico Rosberg believes Lewis Hamilton will have sent a chill down the spines of his rivals by claiming after his record-equalling seventh Formula 1 world title triumph that he is "just getting started".
In the last seven years, only Rosberg has been able to stop Hamilton, with the German winning the 2016 title before opting to retire.
Rosberg, though, could not help but be impressed by Hamilton's latest championship success, and the manner of his victory drive in Sunday's Turkish Grand Prix that allowed him to match Michael Schumacher's seven-title haul.
"No one would have ever thought that Michael Schumacher's titles would be equalled or broken, and yet now he's there," Rosberg told Sky Sports News.
"I think it's not only one of the best and successful Formula 1 achievements but it's one of the greatest achievements in sporting history as a whole."
With Hamilton yet to sign a new deal with Mercedes, the 35-year-old's rivals may be holding onto a modicum of hope he may yet call time on his career.
Hamilton, however, did remark he is "just getting started", words that Rosberg feels will likely have alarmed the rest of the field.
"I think to hear that for the opposition is going to be a bit of a scary thing," said Rosberg.
"For the likes of [Valtteri] Bottas or [Max] Verstappen or [Sebastian] Vettel or whoever else is still out there, if he's saying it's just the beginning, my goodness, what's he going to end up with?
"I'm going to be interested to follow his decisions, what he decides to do going forward since he hasn't done a contract yet for next year."
Rosberg refused, though, to be drawn into the debate as to where Hamilton sits in the pantheon of greats.
"I'm not going to say here and now one is better than the other, I think they're there or thereabouts," insisted Rosberg.
"You'd mention Schumacher, you'd mention [Ayrton] Senna, you'd mention [Juan Manuel] Fangio. I would probably filter out those four - Lewis, Senna, Fangio and Schumacher.
"Who's the best? It's just impossible to say but equally in their own way they've all been just unbelievable."
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