Djokovic collapsed on his back and ripped his shirt open after triumphing in the nearly four-hour contest to get revenge for his loss to the young Spaniard in last month's Wimbledon final.
"So much to say and so little energy," Djokovic said while collecting his third Cincinnati Open title.
"It has been a roller coaster and definitely one of the toughest and most exciting matches that I've ever been a part of in any tournament.
"It did feel like a Grand Slam final, even more than that, to be honest."
The Serb was hobbled by the intense humidity in the tail end of the first set, barely moving when Alcaraz hit a backhand winner to grab the opener.
Alcaraz raced out to a 4-2 second-set lead and it appeared he might cruise to the finish line as his 36-year-old opponent looked cooked in the Ohio sun.
But Alcaraz would produce a poor service game while leading 4-3 that included four unforced errors to give life to the world number two.
In the second-set tiebreak Djokovic saved a championship point and went on to force a deciding set after winning a 25-shot rally.
During the break before the third set, a frustrated Alcaraz pounded his right hand against the plastic drinks container next to his chair, requiring a medical time out to tape his finger.
In the decider, Djokovic broke for a 5-3 lead but would then squander two match points in the next game.
The drama would continue when Djokovic missed an overhead for 5-5 and the players would ultimately arrive at another tiebreak, which Djokovic won on his fifth match point of the contest.
"It is going to be tough for me to talk right now but I tried to do my best," Alcaraz said.
"I want to congratulate Novak once again. It's amazing to play against you, share the court with you, learn from you. This match was really close but I learned a lot."
The win delivered Djokovic his 95th career title and 39th Masters 1000 crown.
The tournament was Djokovic's first on U.S. soil in two years after he was barred from entering the country because he is not vaccinated against COVID-19.
He will look to add a 24th Grand Slam trophy to his collection at the upcoming US Open, which runs from August 28-September 10.
"Every one of our matches goes the distance," Djokovic said to Alcaraz. The pair are now 2-2 in their generational rivalry.
"Hopefully we can play in some weeks' time in New York," he said.
"That would be nice for the crowd, I don't know about me."
