TOKYO (AFP) - Defending champion and top seed Rafael Nadal survived an early scare as he and second seed Andy Murray rolled into the quarter-finals of the Japan Open on Thursday in Tokyo. David Ferrer, the third seed from Spain, also advanced, but not before dropping a set to Australia's spirited qualifier Matthew Ebden. Nadal, who was playing his first singles tournament since losing the US Open final last month, admitted the big-serving Milos Raonic had caused him some headaches in the 7-5, 6-3 victory. The Canadian, 20, forced down eight aces to leave Nadal stumped early on. "At the beginning of the set I didn't have one chance to return his serve. I lost the first two games on his serve without winning one point," said Nadal, 25. "But I felt I started to return his serve more, so I felt I was closer to break than at the beginning." In the quarter-finals on Friday, Nadal will take on Santiago Giraldo of Colombia, winner over Dmitry Tursunov of Russia, 6-4, 7-6 (7/4).