The 22-year-old set-up a meeting with the world number four following a five-set victory over Jo Wilfried-Tsonga earlier today.
Discussing his upcoming match with Murray, Nishikori has claimed that everybody will be expecting the Brit to emerge victorious.
"I played Andy at the end of last year," Nishikori told reporters. "He kind of destroyed me.
"But, I have no pressure now. It's going to be tough, but I have to try and play my best tennis against him.
"He's one of the players I have to play like [to improve]."
Nishikori has previously never reached the quarter-final of a Grand Slam.