Roger Federer won his 99th career title at the Swiss Indoors in Basel and the 37-year-old had the chance to win his 100th this week at the Rolex Paris Masters, but he lost to Novak Djokovic in the semi-finals.
Khachanov won the Kremlin Cup in Moscow last month for his third career title.
Coming into the match, all attention was on Djokovic's bid for a record-tying 33rd Masters 1000 title and 23rd straight match win, but it was Khachanov who extended his own run of 11 wins in 12 matches.
'So all the credit to him.
"As I said for the French Open, I will decide at the end of the year to see how it will have an impact on my physical training".
"I'm getting into the season finale with a lot of confidence and feeling good about my game".
Then, with Djokovic clearly breathing harder, he earned the decisive break to go 2-1 up in the second set after the Serbian pushed a weary-looking backhand into the net.
Djokovic seemed agitated at times and twice turned to his box to remonstrate about an unspecified issue during the first set. The Russian won the first set with a big first serve that Djokovic could not return, stretching out his racket in vain as the fizzing ball clipped the frame.
Khachanov broke early in the second set and threw away three further break points in the seventh game, but was able to capitalise on his advantage and hold on for the win.
"It depends on how I'm playing, how my body feels".
Still, the Wimbledon and U.S. Open champion has plenty to feel good about after a 22-match winning streak, and he remains favorite for the season-ending ATP Finals in London, beginning November 11.
But world number 18 Khachanov, unbeaten in three previous finals, hit back in the very next game as Djokovic dragged a forehand into the tramlines, down break point.
Khachanov became the third different first-time victor of a Masters tournament this year - joining John Isner and Juan Martin del Potro - and denied Djokovic a fourth title in a row ahead of his return to world number one on Monday.
"I'm satisfied of course and I'm going to be No. 1 tomorrow officially".
"It means the world to me", Khachanov said after the match.
"The second thing is after some tough loses against top guys like Rafa in NY, I think they push me to the limit and even to work more harder".