"Don't leave tennis, man," Djokovic said in an on-court interview after beating Nadal in straight sets 6-2, 7-6 (7/5) at the "Six Kings Slam" exhibition in Saudi Arabia.
Nadal, 38, announced on October 10 that he would retire from tennis after the Davis Cup Finals in Malaga next month.
Organisers of the Saudi event billed Saturday's match as perhaps Nadal's last singles contest as a professional.
Nadal said Thursday he was unsure whether he would be fit enough to play singles in Malaga.
Djokovic and Nadal – two of the sport's famed "Big Three" along with Roger Federer - had faced each other 60 times on the main tour prior to Saturday's exhibition match, with Djokovic holding a narrow 31-29 edge.
Their last encounter came during the Paris Olympics on the same Roland Garros courts where Nadal won 14 French Open titles, though Djokovic triumphed easily 6-1, 6-4.
Djokovic, 37, said on Saturday the rivalry had been "very intense" and told Nadal he hoped they could one day "sit on a beach somewhere" and have a drink.
Nadal, who was presented with a golden tennis racket after the match, in turn thanked Djokovic for the "amazing rivalry" and "for all the moments that we shared on court".
After losing to Carlos Alcaraz in straight sets during his first match at the Saudi exhibition on Thursday, Nadal acknowledged his fitness level was well off the tour's top players.
French Open and Wimbledon champion Alcaraz was set to take on Australian Open and US Open winner Jannik Sinner in the "Six Kings Slam" final later Saturday.
Saudi Arabia's push into tennis took off last year with its first ATP Tour event - the Next Gen ATP Finals in Jeddah – and exhibition matches pitting Djokovic against Alcaraz and Aryna Sabalenka against Ons Jabeur.
The Women's Tennis Association (WTA) announced in April that Riyadh would host the next three editions of the Tour Finals featuring the top eight singles players and doubles teams.
The 2024 edition will be staged from November 2-9.
