Djokovic, who will still overtake Rafael Nadal as world No 1, had no answer for the 22-year-old, who had sent Dominic Thiem tumbling out of the Paris Masters in the semi-finals on Saturday. "I won the match, but if he would've won it, it would've been absolutely deserved".
"No idea if it was the last match", Federer replied when asked whether Saturday's loss to Djokovic could be the final time he plays in Paris.
Cilic, who defeated Djokovic in the final at Queen's Club in the summer, was a break ahead for a 2-1 lead in the decider.
Instead, up against a great champion looking for a fourth consecutive tournament win, following his victories at the Cincinnati Masters, the U.S. Open and the Shanghai Masters, the chess-loving Russian changed his strategy. Khachanov continued his strong recent form and easily won the second set 6-1 to reach the final to play against Novak Djokovic.
The Japanese consequently appeared to lose all composure, gifting Federer another break at the start of the second.
Novak Djokovic marks return to world number one with Paris win
Sock goes up against Dominic Thiem on Friday after the 2018 French Open finalist edged Borna Coric 6-7 (3-7) 6-2 7-5. The 31-year-old has been in top form this week but faces a hard last-eight opponent in Marin Cilic tomorrow.
The 22-year-old, 6ft 6in Russian, already the owner of two indoor hard court titles this year, crushed his Austrian friend and practice partner in 70 one-sided minutes.
"Paris. I played some good tennis so I can be happy", he pointed out.
"When you are losing, maybe you get frustrated from some calls from somebody in the crowd and maybe he was pissed, I don't know, that somebody from my box screamed on his mistake and that was the reason", Khachanov told Sky Sports afterwards.
Khachanov became the third different first-time victor of a Masters tournament this season - joining Juan Martin del Potro and John Isner - and will rise to a career-high ranking of 11th on Monday.
Mother reunited with son kidnapped 31 years ago
Officials say the elder Mann had abducted his son during a court-ordered visit in 1987, and then fled across the border. The local paper reported that Jermaine sobbed quietly in the front row with his head in his hands.
"To finish the season like this is really a dream come true". Federer saved both break points, prompting Djokovic to smash his racket into the ground.
The 31-year-old, now unbeaten in 22 matches, is a four-time victor of the Paris Masters.
"I told him my shoulder is hurting and that his uncle, or something, that he's going a bit insane", he said.
Khachanov added this title to the Kremlin Cup in Moscow last month for his third title of the year and fourth overall.
Djokovic and Federer have clashed at all four Grand Slam tournaments and eight of the nine ATP World Tour Masters 1000 events.
Gaza rockets hit Israel after five Palestinians killed in border flareup
The Islamic Jihad group claimed responsibility for the rocket attacks, saying they were in response to the deaths on Friday. Hamas has demanded a full lifting of the blockade, which has made it increasingly hard for Hamas to govern.