But having become the first Japanese man to reach the quarter-finals since Shuzo Matsuoka in 1995, Nishikori must now overturn a 13-2 career losing record against three-time champion Djokovic on Wednesday.
"He's always like a big war for me. I always enjoy playing against him. It's always big challenge," said Nishikori.
Although the two have never met on grass, Nishikori is still hamstrung by the knowledge that the last of his two wins against the Serb was in 2014 in a memorable semi-final victory at the US Open.
"Maybe I don't have good results or good record with him, but I always enjoy playing him.
"He's one of the best players on the tour."
Adding to Nishikori's problems is a worrying right arm injury which required extensive treatment and a medical time-out in his win over world 130 Gulbis, the man who had put out fourth seed Alezander Zverev in the third round.
"My elbow was bothering me little bit," admitted Nishikori.
"From the second, it got better and I just tried to stay calm and fight every game." Djokovic, meanwhile, reached the quarter-finals for the 10th time with a 6-4, 6-2, 6-2 win over Russia's Karen Khachanov.
Seeded 12, Wednesday will Djokovic's 41st appearance in a Grand Slam quarter-final.
His match against Nishikori will fall on the first anniversary of him having to retire from his 2017 quarter-final against Tomas Berdcyh with an elbow injury. That precipitated a lengthy absence from the tour and a worrying dip in form and confidence.
However, the 31-year-old has looked back to something approaching his best at Wimbledon.
"I like my chances against Nishikori," said Djokovic.
He added: "I played very well in Queen's (where he finished runner-up) coming into Wimbledon.
"I haven't spent too much time on the court. I feel physically, mentally ready, fit, positive."
Djokovic's run to the Queen's final on the eve of Wimbledon was his first appearance in a championship match since Eastbourne almost 12 months earlier. That was a boost after a shock quarter-final exit at the French Open to world number 72 Marco Cecchinato of Italy.
"I didn't feel comfortable on the court for long time. Indian Wells, Miami, most of the clay court season," added Djokovic.
"I just had to go back to basics and hit as many balls as I can on the practice courts, just get that feel.
"Also psychologically obviously, I was so fortunate to have so much success on the tour over the course of 10-plus years.
"I was top 3 player for so many years in a row, it was quite a strange feeling for me not to be able to deliver my game.
"But things are looking much better in the last month and a half.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)