"I think the rain helped me a lot, because I was really down in the fourth set and mentally I wasn't ready", said Nishikori, whose only Grand Slam final appearance came when he lost at the 2014 US Open. "It's very important for me to be in the quarter-finals one more time", he said.
"I'm happy about these four matches". "All in all, it was good to be part of five-set match", said Djokovic. 0-2 in Rome, 0-1 at last year's World Tour Finals, 1-4 at Roland Garros, and the kicker, an appalling 1-15 at Miami, which was their most competitive match, a surprise given it was on a hard surface and not clay.
And with the Austrian crushing Horacio Zeballos 6-1 6-3 6-1 in the fourth round, it's certain that he will provide a stiff test. However, fourth-round opponent Kristina Mladenovic, the French number one, will have the majority of the crowd behind her on Court Philippe Chatrier.
While the pair have met five times in their history, with Djokovic winning all of them, it was the semi-finals past year which the former world no.1 can use to his advantage.
Finally, Switzerland's Timea Bacsinszky defeated 2002 runner-up Venus Williams 5-7, 6-2, 6-1, while Danish 11th seed Caroline Wozniacki knocked out 2009 champion Svetlana Kuznetsova 6-1, 4-6, 6-2 to reach the last eight for just the second time. It appeared the favored Djokovic was perhaps in for a long day, but he responded to the battle of attrition in the first set by steamrolling Ramos-Vinolas in the second.More news: Portugal vs Mexico FIFA Confederations Cup
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"Everything wasn't flawless. There were a few concerns", Mladenovic said, before joking: "I made about 35 double-faults today, but everything's OK!" Since 2005, she has only lost once to a player who would not make a French Open semifinal: her third-round defeat by Gisela Dulko in 2011. Gael Monfils also advanced in Paris when his compatriot Richard Gasquet retired midway through the third set.
Eighth seed Nishikori led two sets to one but trailed by a double break at 3-0 down in the fourth set when rain halted play on Saturday.
The 26-year-old Martic next faces fifth-seeded Elina Svitolina after the Ukrainian beat Magda Linette 6-4, 7-5.
The second-seeded Pliskova hit 34 winners as she raced to a 7-5, 6-1 victory in 70 minutes.
It was the first time in the Open era that two Asian men had met as late as the third round in a Grand Slam tournament.