MIAMI (AFP) - Swiss Roger Federer cruised through while top seed Rafael Nadal survived a stiff challenge as both reached the quarter-finals of the ATP and WTA tournament on Tuesday with straight-set triumphs. Federer rolled over American qualifier Taylor Dent 6-3, 6-2 while Spaniard Nadal was made to work for his 7-6 (7/2), 7-6 (7/4) win over Swiss No. 16 seed Stanislas Wawrinka. Federer needed just 85 minutes to earn a berth in the final eight by ousting 27-year-old Dent who squandered eight break-point chances. "I had to come up with some good passing shots to be able to make a difference," Federer said. "He might have got a bit tired towards the end." Nadal needed two tiebreaks to beat the pesky Wawrinka in the two hour, 42 minutes marathon match. Wawrinka jumped out to a 3-1 lead in the second set before Nadal clinched it 7-4 in the final tiebreak. Nadal and Wawrinka traded blows in the first set then Nadal stepped up his game in that tiebreak winning 7-2. "Important win for me here. Very important," Nadal said. "To be in quarterfinals is always a good result. "I was very focused and I played two good tiebreakers, so that's very good."Russian eighth seed Svetlana Kuznetsova became the first semi-finalist in the women's draw by beating Danish 13th seed Caroline Wozniacki 6-4, 6-7 (5/7), 6-1. The 2006 champion will play in the semi-finals Thursday against No. 11 Victoria Azarenka, who beat unseeded Samantha Stosur 6-1, 6-0.Nadal's victory means eight of the top 10 seeds are into the quarter-finals for the first time in the tournament's 25-year history. It is also the first time there are eight seeds in the quarter-finals. "I think that's good for tennis," Nadal said. "And I think we are in one moment of the tennis history that the best players are always winning. "For that reason winning titles is almost more difficult than ever. Because all the time you have to play against the best." Federer advances to the next round where he will face fifth seeded American Andy Roddick who advanced with a 7-6 (7/2), 6-4 win over France's Gael Monfils. "We've had some big matches over the years," Federer said of Roddick. "I played him at the Australian Open and played well against him. He seems like he changed a couple of things in his game so it should be a good match." Serbian third seed Novak Djokovic also took a 6-3, 6-2 victory over Czech Tomas Berdych while British fourth seed Andy Murray routed Djokovic's Serbian teammate Viktor Troicki 6-1, 6-0. Scotsman Murray will next face eighth-seeded Spaniard Fernando Verdasco, who bounced Czech 18th seed Radek Stepanek 6-2, 6-2. "I didn't make a lot of mistakes, high percentage of first serves, used my slice well - just kept thinking all the way through the match," Murray said. "Right from the start, to get a break early, set the tone for the rest of the match. He didn't really recover from that." Djokovic, who won the Miami crown in 2007, pounced upon Berdych's every mistake to advance. "I was trying to stick with him all the time, because I knew he's very aggressive, but not really consistent from the baseline," Djokovic said. "He makes a lot of unforced errors, especially from the forehand side, so I changed the pace and I played a really good tennis." Djokovic will next face French 10th seed Jo-Wilfried Tsonga, who eliminated seventh-seeded countryman Gilles Simon 6-7 (4/7), 6-3, 6-2 in another fourth-round match. Tsonga, who felt slightly ill before the match, is the first Frenchman in a decade to reach the quarter-finals at Miami. And Djokovic knows he is in for a fight. "I lost to Tsonga four times in a row, so he has a little advantage probably there," Djokovic said. "But I think all the matches we played were very close so it's going to be a challenge for me to win." Kuznetsova fell the court in exhaustion at the completion of her two hour, 54-minute match in the mid-day heat. "I was until 5-3 feeling very comfortable out there, but I got so dizzy and tired," Kuznetsova said. "The conditions played a big role in my game." Wozniacki extended the match from 6-4, 5-2 down, but the Dane lost all momentum at the start of the third set.