Novak Djokovic and Rafa Nadal progress in Miami but Andy Roddick falls World number one Novak Djokovic and second ranked Rafa Nadal moved into the quarter-finals of the Sony Ericsson Open with straight set victories last night. Djokovic, a 7-5 6-3 winner against Richard Gasquet, had a game on his hands in the opening set when he was broken in the fourth game by a fine backhand winner from the Frenchman. The Serb, the defending champion, broke back in the sixth only to face break point in the ninth game, but three times he held firm and was able to emerge with the set. The Frenchman's determination faded in the second set as Djokovic broke in the fourth and sixth games to run out winner in one hour 40 minutes. Djokovic will play Spain's David Ferrer who beat Argentine Juan Martin Del Potro 6-3 6-3. Nadal, a three-time finalist at the Miami Masters series event, beat 16th seed Kei Nishikori of Japan 6-4 6-4. The Spaniard made a sluggish start but Nishikori missed out on six of seven break point chances in the opening three games. A forehand smash allowed Nadal to break and wrap up the first set and then it was easier going in the second set for Nadal despite a late push by Nishikori. The beginning was very tough for me. I think I started playing more aggressively, I started playing shorter and so I suffered a lot with my serves the beginning of the match," said Nadal. But later, at the end of the first set, I felt that I was starting to win my serves more easily than him. So the last couple of games of the end of the first set, I believe that I had more the control of the game. Nadal will face Jo-Wilfried Tsonga of France in the quarter-finals, after he defeated Florian Meyer of Germany 6-3 6-2. Andy Murray beat Gilles Simon 6-3 6-4 to set up a quarter-finals matchup with Janko Tipsarevic, who earlier beat unseeded Bulgarian Grigor Dimitrov 7-6 6-2. In other fourth round action, American Mardy Fish fought past Spaniard Nicolas Almagro 6-3 6-7 6-3 and will face Argentine Juan Monaco. Monaco beat Andy Roddick 7-5 6-0, the American failing to build on his surprise victory over world number three Roger Federer on Monday.