Djokovic's last run to the final four at Wimbledon ended with him winning the tournament and he then went on to lift the 2015 US Open and 2016 Australian and French Open titles, becoming only the third man to hold all four Grand Slam trophies at the same time.
It was performance of resilience and resolve from the former number one, reminiscent of the player who held all four Grand Slam titles two years ago.
"It felt like it was getting better and better as matches and time went on".
"Do you think or not?"
The semi-final will be the 32nd of Djokovic's Grand Slam career but he has had to fight to get there.
The Serbian, Djokovic, maintained the dominance he has shown throughout the tournament on his first serve.
"It gives me confidence that I was able to play good tennis on grass", Nishikori said.
"To be honest, I thought it was unnecessary to get a warning".
Nishikori capitalised on this lapse in concentration, putting together his finest game of the match to break and then consolidate.
"I feel like I'm peaking at the right moment", declared the 12th seeded Serb after joining Americans John McEnroe and Pete Sampras in fourth place on the list of most Wimbledon semi-final appearances in the Open Era.
Nishikori is also on his way back up after injury, and the outcome could easily have been different had the Japanese won the game where he had Djokovic at 0-40 early in the third set.
Djokovic, seeded 12th, was visibly disappointed at those missed opportunities, incurring a warning from umpire Ramos for throwing his racket, and Nishikori made him feel even worse when he broke to lead 3-1 after Djokovic put an attempted drop shot into the net.
'I didn't harm the grass.
After a slump following two years of nearly total domination of the men's game, Djokovic's star appears to be back on the rise and he is a clear contender to win a fourth Wimbledon title.
As he soaked in the applause of the crowd, win secured, there was that old Djokovic again, lapping up the acclaim, turning his hands to the sky and then conducting the crowd in their ripples of cheering. "I get the warning, he doesn't, so it's not fair". "I really do", Djokovic said.
"It motivates me to do extremely well here because I don't want to sit here and explain my loss".
The three-time Wimbledon champion was broken in the opening game of the fourth set, but won the next four games and broke again to clinch victory.