Australian Nick Kyrgios is through to the last 16 of the Miami Open after a straight sets victory over American qualifier Tim Smyczek.

Kyrgios defeated Smyczek 6-4, 6-4 in 87 minutes to book a match-up with unseeded Russian Andrey Kuznetsov.

The 24th seed is yet to drop a set in the tournament.

Kuznetsov defeated Frenchman Adrian Mannarino in a tough three setter to advance to the fourth round.