Defending champion Andy Murray survived a testing encounter with Stanislas Wawrinka to reach the quarter-finals of the Shanghai Masters Thursday as David Ferrer saved three match points to progress. Second seed Murray, on a red-hot run of form of 21 wins from 22 matches coming into the clash against the Swiss 13th seed, won 6-4, 3-6, 6-3 under the roof at the Qi Zhong stadium. The British player looked set for a straightforward victory after taking the first set but cut a frustrated figure as he conceded a break of serve in the second set as Wawrinka levelled the match with an ace. Murray raced into a 5-0 lead in the decider as Wawrinka was warned by the umpire after smashing his racket but despite a late wobble, he closed out the match and remains on course for a final clash against top seed Rafael Nadal. Earlier, Spain's Ferrer edged into the last eight when he beat injured Juan Carlos Ferrero. Third seed Ferrer won the all-Spanish tie 1-6, 7-5, 6-2 after a major fright in the 10th game of the second set, when he was forced to dig deep to hold serve and prevent Ferrero from sealing the win. The win for Ferrer means he becomes the fifth player to qualify for the season-ending ATP World Tour Finals, featuring the world's top eight singles players over the year. "I served very well in important moments," said the Spaniard, referring to how he saved the match points. "I won this game, and after this game I made the break very fast. Maybe Juan Carlos, he was a little bit injured. Maybe in the third set it was more easy." Speaking about qualifying for the season-ending showpiece, Ferrer said: "I think this season I have played really good tennis. I am very consistent. Maybe it is my best year of my career. I think so." Injury-cursed Ferrero had strapping applied to his right ankle midway through the second set after a nasty tumble and although he recovered to force the match points, his challenge faded in the third set. American 10th seed Andy Roddick reached the last eight after an impressive 6-3, 6-4 win over Nicolas Almagro, seeded seven, of Spain. Roddick secured a single break in each set, wrapping up victory with his 11th ace in a controlled display that saw him make just 14 unforced errors. Ukrainian 12th seed Alexandr Dolgopolov also reached the quarter-finals, beating Australian teenager Bernard Tomic while Japan's Kei Nishikori triumphed over Santiago Giraldo of Colombia.