(CNN) -- World number one Rafael Nadal reached the fourth round of the ATP and WTA hardcourt tournament at Key Biscayne in Florida on Monday with a 7-5 6-3 success over Portugal's Frederico Gil.
Nadal's strength of serve helped him score a comfortable win to reach the round of 16 at the Florida event.
Nadal, who took the year's first Grand Slam title by defeating Roger Federer in the Australian Open final, won 89 percent of his first serve points to just 57 percent for Gil.
The Spanish star was joined at the next stage by Briton Andy Murray who defeated Nicolas Massu 6-4 6-4.
Massu, a former top-10 player now ranked 91, produced a series of trademark blistering forehands to dominate much of the opening set but lost his temper and focus to hand Murray a comfortable win.
The British number one will now face Serbia's Viktor Troicki ahead of a possible rematch with Fernando Verdasco, the man who defeated him in the Australian Open quarterfinals.
Australian Samantha Stosur, ranked 42nd, continued her strong run into the quarterfinals by ousting French 20th seed Amelie Mauresmo 6-4 6-4.
Stosur, who eliminated Russian world number two Dinara Safina in the third round, will next meet 11th seed Victoria Azarenka of Belarus, who defeated Hungarian 25th seed Agnes Szavay 6-2 6-4.
US fifth seed and three-time champion Venus Williams ousted Polish 10th seed Agnieszka Radwanska 4-6 6-1 6-4 to reach the final eight.
Danish 13th seed Caroline Wozniacki shocked fourth seed Elena Dementieva 7-5 6-4 and next faces another Russian, eighth seed Svetlana Kuznetsova, who beat compatriot Alisa Kleybanova 6-2 6-1.
Others reaching the men's round of 16 included Argentina's sixth-seeded Juan Martin Del Potro, who beat Serbian Janko Tipsarevic 6-4 6-1, and Serbian Viktor Troicki, who ousted Germany's Bjorn Phau 6-4 6-3.