World No.1 Rafael Nadal has battled his way into his 10th Australian Open quarter-final with a hard-earned four-set win over dogged Argentine Diego Schwartzman.
Nadal dropped his first set of the tournament before regrouping to move into the last eight with a 6-3, 6-7 (4-7), 6-3, 6-3 victory in three hours and 51 minutes tonight.
Spain's 16-time grand slam champion will play 2017 Wimbledon runner-up Marin Cilic for a semi-final spot on Tuesday after the big-serving Croat recorded a similarly tough 6-7 (2-7), 6-3, 7-6 (7-0), 7-6 (7-3) win over 10th seed Pablo Carrena Busta.
"A great battle," Nadal said after finally seeing off Schwartzman after three hours and 51 minutes on Rod Laver Arena.
"He's a great player in all aspects and I feel that for a lot of moments he was serving well this afternoon.
"That is something he is normally so comfortable with."
After being restricted to one match in three months before the Open, Nadal said he was finally feeling confident in his knees again and ready to make for another serious second-week push for a second title.
"It's the first big match of 2018. I started later than usual ... so one match like this probably helps," said the the 2009 Open champion and three-time runner-up.