John Isner has defeated Nick Kyrgios in three sets to book his place in the quarter-finals of the Madrid Open.

The Australian youngster ousted Roger Federer in a thrilling contest on Wednesday evening, but he was unable to keep his campaign on track in the Spanish capital.

Isner made a strong start to the contest, holding his serve throughout the opening set to prevail 6-3 in a rather straightforward fashion.

He managed to hold in the second set, too, although Kyrgios showed more of his battling qualities by doing likewise to force a tie-break.

World number 18 Isner blew the chance to see off his opponent in straight sets by squandering a match point, and that allowed the Australian to level things up.

The deciding set proved to be just as tense, but it was Isner who showed his experience to keep his nerve and take the match 6-3 6-7(7) 6-4.