Andy Murray may well have breathed a sigh of relief, having been given a walkover into the fourth round of the Sony Ericsson Open in Miami.

The Scot was set to play against Milos Raonic, the man whose serve has earned him the nickname 'The Missile', but the Canadian pulled out with an ankle injury.

Raonic, 21, and one of the brightest prospects in tennis, suffered the injury in practice and lasted just three games of a doubles match the previous night.

Murray can now look forward to his next match tomorrow against Gilles Simon of France, who defeated Austria's Jurgen Melzer 7-6 (7-5), 6-4. Murray leads Simon 8-1 in their head-to-head meetings.

Rafael Nadal was a convincing third-round winner as he raced past Czech player Radek Stepanek.

The Spanish second seed was hardly troubled as he won 6-2 6-2 to set up a last-16 tussle with Japan's Kei Nishikori.

Nishikori, seeded 16th, came through 6-4 6-2 against Czech Lukas Rosol.

It was a particularly poor day for the Czech players. Seventh seed Tomas Berdych was another casualty among their number as he lost 6-3 2-6 6-4 to rising Bulgarian star Grigor Dimitrov.

Ninth seed Janko Tipsarevic is next for Dimitrov, after edging past Alexandr Dolgopolov 6-4 5-7 6-2.

Jo-Wilfried Tsonga was given a workout by Philipp Kohlschreiber, the Frenchman knocking out his German opponent 6-4 7-6 (7/2). And Tsonga will tackle another German next, 19th seed Florian Mayer knocking out heavy-serving American John Isner 6-4 6-2.

Meanwhile, Scotland's Colin Fleming and Englishman Ross Hutchins will today bid for a place in the doubles quarter-finals when they take on Leander Paes and Radek Stepanek.