NEXT HURDLE:Top seeds eye gloryANDY Murray joined world number one Novak Djokovic and second seed Rafael Nadal in the quarter-finals of the Miami Masters, all three progressing in straight sets.After narrowly surviving a 17-minute opening game, Murray made light work of a tricky opponent in Gilles Simon, beating the Frenchman 6-3 6-4 in one hour and 46 minutes.Djokovic endured a tough first set against Richard Gasquet before running away with proceedings to triumph 7-5 6-3 while Nadal was forced to survive a late fightback from Kei Nishikori to secure a 6-4 6-4 win.Next up for Murray will be Serbia’s Janko Tipsarevic, who progressed to the quarter-finals with a 7-6(3) 6-2 win over Grigor Dimitrov of Bulgaria.Australian Open champion Djokovic made a sluggish start to his clash with Gasquet, suffering a break of serve in just the fourth game of the match when the Frenchman found the target early with a trademark backhand.Next up for Djokovic is David Ferrer, who delivered a masterclass to send Juan Martin Del Potro packing from the tournament.The Spanish fifth seed dismantled his Argentine opponent in a hugely impressive 6-3 6-3 victory in the final match to finish under the floodlights on Stadium court.Nadal appeared to be cruising against Nishikori with a set and a break lead only for Japanese 16th seed to break back with a drop shot.But the Spaniard weathered the storm and broke back in the 10th game of the set, to reach the last four for the seventh time.Next up for Nadal will be a clash against sixth-seeded Jo-Wilfried Tsonga, who made incredibly light work of Germany’s Florian Mayer, beating the 19th seed 6-3 6-2.Eighth seed Mardy Fish survived a tough match when he battled past 12th seed Nicolas Almagro 6-3 6-7(2) 6-3.Fish was denied the chance of an all-American quarter-final, however, when Andy Roddick crashed out of the tournament 7-5 6-0 at the hands of 21st seed Juan Monaco.Roddick, seeded 31 in Miami, looked a shadow of the player who beat Roger Federer 24 hours previously and produced a lacklustre performance that his Argentine opponent took full advantage of.