INDIAN WELLS - Defending champion Roger Federer and Rafa Nadal set up a mouth-watering showdown in the BNP Paribas quarter-finals after they battled through tricky fourth-round encounters on Wednesday.Federer rode his luck to scrape past fellow Swiss Stanislas Wawrinka 6-3 6-7 7-5 while Nadal had to come from a set down to beat talented Latvian qualifier Ernests Gulbis 4-6 6-4 7-5.Four-times Indian Wells champion Federer last played Nadal a year ago, also at Indian Wells, when the Swiss won their semi-final 6-3 6-4, though the Spaniard leads overall in their meetings 18-10.Australian Open champion and top seed Novak Djokovic, who began his "evening” match in the early hours of Thursday morning local time, advanced with a 6-0 7-6 victory over big-serving American Sam Querrey.Third seed Andy Murray needed almost two hours to beat Carlos Berlocq of Argentina 7-6 6-4 and will next face seventh-seeded Juan Martin Del Potro of Argentina, who overpowered German Tommy Haas 6-1 6-2."Today it was extremely close again,” Federer told reporters after coming out on top of a fluctuating contest lasting two hours 20 minutes. "He usually plays me pretty good actually overall.In other matches, sixth-seeded Czech Tomas Berdych eased past Frenchman Richard Gasquet 6-1 7-5 while eight-seeded Jo-Wilfried Tsonga came from a set down to beat Canada’s Milos Raonic 4-6 7-5.