World number one Rafael Nadal needed two tie-breaks to outlast Stanislas Wawrinka 7-6, 7-6 at the Sony Ericsson Open on Tuesday, the Spaniard's win completing an ominous march into the quarter-finals for the top seeds.
Earlier, second seed Roger Federer enjoyed a comfortable 6-3, 6-2 win over American qualifier Taylor Dent to set up a clash against local favorite Andy Roddick, while Britain's Andy Murray crushed Serbian Viktor Troicki in just 58 minutes 6-1, 6-0.
Third-seed Novak Djokovic also advanced with a routine 6-3, 6-2 win over Czech Tomas Berdych, setting up a quarter-final showdown with Frenchman Jo-Wilfried Tsonga, who rallied for a 6-7, 6-3, 6-2 win over compatriot Gilles Simon.
Nadal and his Swiss opponent slugged it out for two hours and 43 minutes in the match of the tournament to date, with both players displaying high levels of determination and quality.
The first set went with serve before Nadal seized the tie-break 7-2 and the excitement intensified in the second.
Wawrinka bamboozled Nadal with two excellent lobs to break in the fourth game but the Spaniard broke back and looked to have the contest wrapped up when leading 6-5 and 40-0 on his opponent's serve.
However, Wawrinka refused to buckle and saved four match points to force the set into a tie-break, which the Spaniard took 7-4 to finish off his 24-year-old opponent's gutsy challenge.
Nadal, enjoying plenty of support from the Latin-Americans in the crowd, will face Argentine Juan Martin Del Potro, a 6-3, 6-2 victor over Spain's David Ferrer.
American Dent -- returning to the main tour after a career-threatening injury in 2007 -- showed plenty of fight but never appeared likely to upset the Swiss right-hander, who won 83 percent of first service points.
Roddick, who is looking to capture a second Miami title after his 2004 triumph, made a slow start to his match against Gael Monfils before emerging with a 7-6, 6-4 victory over the Frenchman.
The ninth-seeded Monfils had the chance to serve out the opening set when leading 6-5 but Roddick recovered the break and went on to win the tie-break 7-2.
The second set was easier for Roddick, who broke in the third game and comfortably held serve to secure victory.
The fourth-seeded Murray moves on to a quarter-final against Spain's Fernando Verdasco, who beat Czech Radek Stepanek 6-2, 6-2. Murray will be looking for a measure of revenge against the eighth seed after losing to him at this year's Australian Open.
"I didn't make a lot of mistakes, won a high percentage of first serves and used my slice well. I just kept thinking all the way through the match," Murray told reporters.
"Right from the start, to get a break early that kind of set the tone for the rest of the match. He didn't really recover from that."