Roger Federer's resurgence has continued after he battled his way past Roberto Bautista Agut to reach the quarter-finals of the Miami Open.

The world number six took two hours to claim a 7-6(5) 7-6(4) victory to set up a final-eight showdown with Tomas Berdych, who earlier defeated Adrian Mannarino.

It was difficult to separate Federer and Bautista Agut in the first set as games went by the way of serve in the early stages of the contest.

The Spaniard thought that he had taken the edge when he went a break up to secure a 5-4 lead, but Federer prevented set point by breaking back immediately.

The 18-time Grand Slam champion broke just once to seal a tie-break 7-5, and he carried that momentum into the second set by snatching serve at the first time of asking.

He could not celebrate for long, though, as Bautista Agut broke back straight away and immediately saved three break points in his next service game.

Another tie-break was needed to separate the pair, and once again, Federer snatched it 6-4 to progress into the quarter-finals.