Nick Kyrgios held off Alexander Zverev in a fascinating quarter-final clash to set up a final-four showdown with former world number one Roger Federer at the Miami Open.

In a sign of the future, Kyrgios and Zverev provided plenty of entertainment as the 12th seed needed six match points to prevail 6-4 6-7 (9-11) 6-3 on Thursday.

Zverev - the 16th seed - refused to surrender after saving three match points in a thrilling second-set tie-break but the talented German was unable to fend off a sixth in the decider after two hours, 33 minutes on court.

Kyrgios - into his third semi-final of the year - now has the chance to lock horns with 18-time grand-slam champion Federer after food poising forced him to withdraw from their quarter-final contest at Indian Wells last week.

It was a relaxed and strange opening between the two players as Kyrgios - who ousted Zverev last week - put on a show in Miami on Thursday.

Playing his trademark 'tweener' - a shot between his legs - Kyrgios firstly tried to assist an intrusive bee off the court in the sixth game before a fearless ball boy came to the rescue, picking it up and placing it in his pocket, with the Australian star clearly impressed.

The relaxed nature continued when Kyrgios encouraged Zverev to challenge after his backhand was called long. It proved to be a wise decision as the point was replayed.

Pleased with his honesty, Kyrgios was then overheard saying "I want to see this on social media" as Zverev gave him a thumbs up.

Amid the smiles and thumbs up, Kyrgios and Zverev could not be separated until the ninth game.

A powerful forehand winner down the line earned Kyrgios the first break point of the match which he failed to convert. But he earned another and made no mistake, attacking Zverev's second serve for a 5-4 lead before closing out the first set.

Kyrgios was playing with a spring in his step, demonstrating his confidence and undoubted quality with another unbelievable show between his legs on the line.

It was a matter of Zverev trying to keep his opponent at bay and he did throughout the second set - in complete contrast to the opener.

And Zverev showed steel to fend off three match points in a thrilling tie-break as he forced a deciding set at the third time of asking after Kyrgios sent a tweener into the net.

Kyrgios looked rattled as Zverev oozed confidence in the final set but the latter was eventually broken in the sixth game.

It was an emotional decider and tempers threatened to boil over when Zverev reacted angrily to a late challenge from Kyrgios, who won the point.

Still clearly aggravated by the decision, Zverev lost his concentration and way as Kyrgios booked a spot in the semis, despite fending off another two match points.