Djokovic a two-time US Open champ and 13-time Grand Slam victor, was just that much better than Nishikori in a 6-3, 6-4, 6-2 win to reach his record-tying eighth final in NY.
Twelve months ago, Novak Djokovic wasn't even playing in the US Open while trying rehab a nagging elbow injury that eventually required surgery.
"I just watched that match when I was preparing for this final", Djokovic told Serbian outlet Sport Klub.
The third and final set almost followed the same script, as Djokovic again broke del Potro to take a 3-1 lead only for the Argentinian to break back and level the set at 3-3.
With all the singing and noise levels inside the stadium, it felt to Djokovic like he was at a football match but he thanked the fans of both sides for creating such an incredible atmosphere. I had to kind of disconnect a little bit.
"But I have my personal opinion that maybe the chair umpire should not have pushed Serena to the limit, especially in a Grand Slam final". Delpo then pushes a backhand wide for game point, but Djokovic mixes in his first double fault of the match for either player to deuce. Del Potro is also at a career-high ranking of No. 3.
Del Potro had a 3-1 lead in the tiebreaker before Djokovic recovered to take it.
Juan Martin del Potro stood with his hands on his knees, exhausted from taking the mightiest swings he could with his ferocious forehand.More news: Harry and Meghan's New Zealand tour details revealed
'I have utmost respect for what they have achieved on the court, but also the champions, role models they are off the court.
That seemed to take some of the fight out of the Argentine who went down 7-4 in the eventual tiebreak.
Novak Djokovic celebrates his US Open 2018 victory at the Arthur Ashe Stadium.
"Hard times but you learn from adversity", Djokovic said. "But I love you too, guys", he told the crowd. "I just want to create from this moment onwards the most I can create for myself, to get the best out of myself in every possible moment".
Djokovic faced neither of his greatest rivals en route to the title in Flushing Meadows.
Djokovic went on to congratulate Del Potro for his achievements despite all the injury trouble and made a massively sporting gesture by saying he knew Del Potro will stand as champion at this podium one day. Both players settled for a tie-break in which the 31-year-old Serb rallied from 3-1 down, winning six of the next seven points, to win a mammoth set in 95 minutes and move to within one set of a second straight Grand Slam title. Barty and Vandeweghe kissed the trophy and won $700,000 for their championship.
He closed his win with a yelp, barely audible over del Potro's ebullient fans.