Intro:

All the action from the men's fourth round of the Sony Open in Miami, United States, on Tuesday. There were surprise defeats for world number four David Ferrer and Australian Open champion Stanislas Wawrinka, whilst the other top six seeds Andy Murray, Novak Djokovic, Roger Federer and Rafael Nadal all safely progressed into the quarter-finals.

Script:

World number 20 Kei Nishikori pulled off one of the shocks of the Sony Open in Miami on Tuesday. He sent world number four David Ferrer crashing out in three sets, 7-6, 2-6, 7-6 .

There was another surprise defeat for Australian Open champion Stanislas Wawrinka at the hands of number 22 seed Alexandr Dolgopolov, 6-4, 3-6, 6-1.

Defending champion Andy Murray saw off Frenchman Jo-Wilfried Tsonga 6-4, 6-1 to set-up a quarter-final clash with Novak Djokovic.

Djokovic beat Spain's Tommy Robredo 6-3, 7-5 to ensure he meets Murray for the first time since last year's Wimbledon final.

Roger Federer required just 49 minutes to cruise past Richard Gasquet of France 6-1, 6-2. The Swiss takes on Nishikori in the last eight.

The Florida venue was temporarily locked down when a suspicious package was found but police gave the all clear before Rafael Nadal eased past Fabio Fognini 6-2, 6-2.

The 13-time Grand Slam champion will play Milos Raonic in the last eight, with the Canadian beating Benjamin Becker 6-3, 6-4.

Elsewhere at the Sony Open -- which was originally held in Delray Beach -- the waters closed in on home favourite John Isner, who was beaten 6-3, 7-5 by Tomas Berdych of the Czech Republic.