Federer, who won last week's Indian Wells title as well as the Australian Open in January, continued his stunning form in 2017 with a 7-6, 7-6 win over Agut at the Crandon Park Tennis Center today.

Fourth seed Federer has won two titles in Miami in 2005 and 2006 and has now equalled his best start to a campaign with 16 wins and one defeat.

Federer will now face 2010 Miami Open runner-up Tomas Berdych in the last eight, after the Czech player beat Adrian Mannarino of France 6-3, 7-5.

The tournament's number one seed, Switzerland's Stan Wawrinka, was eliminated from the competition today as he was beaten in three sets by Germany's Alexander Zverev.

Having taken the first set, Wawrinka looked comfortable, but the German made a sublime recovery to secure his place in the next round 4-6, 6-2, 6-1.

Spain's Rafael Nadal also progressed as he defeated France's Nicholas Mahut 6-4, 7-6.

The Spaniard has lost in the final of the Miami Open on four occasions and has never won the title, most recently losing to Novak Djokovic of Serbia in 2014.

Kei Nishikori of Japan is also through to the quarter-finals as he aims to go one better than last year where he lost in the final to Djokovic.

Nishikori defeated Federico Delbonis of Argentina 6-3, 4-6, 6-3.

In the women's singles, Denmark's Caroline Wozniacki reached the semi-finals of the Miami Open with a straight sets win over Lucie Safarova of the Czech Republic.

Wozniacki, who was competing in her sixth quarter-final in seven events this year, clinched a 6-4, 6-3 win.

She will now play the tournament's second seed, Karolina Pliskova of the Czech Republic, for a place in the final after she beat Mirjana Lucic-Baroni of Croatia 6-3, 6-4.

The other semi-final will be confirmed tomorrow.

Great Britain's Johanna Konta is set to face Simona Halep of Romania in one quarter-final with the winner facing either world number one Angelique Kerber of Germany or the United States' Venus Williams.