Murray won 61 percent of the points in the match in cruising to a 6-1, 6-2 victory over Santiago Giraldo. Murray had nine aces and lost his serve just once on the day.
Top-seeded Rafael Nadal, who has won the event six times in the last seven years, lost just 12 points in eight games serving during a 6-2, 6-3 win over Robert Farah. Nadal, in addition to winning 71 percent of the points on serve, took 55 percent off Farah's serve.
No. 3-seeded David Ferrer, who has been the runner-up the last three times Nadal won the tournament, advanced to the quarterfinals with a 6-0, 6-2 victory over Albert Montanes. He saved all four of the break points he faced.
Other match results Thursday saw fifth-seeded Janko Tipsarevic stop Frederico Gil 6-2, 6-2; No. 7-seeded Feliciano Lopez rip past Jarkko Nieminen 6-3, 6-1; eighth-seeded Kei Nishikori top No. 17 Albert Ramos 7-6 (7-2), 6-3; No. 9-seeded Fernando Verdasco cap the day's play with a 6-4, 6-4 decision over No. 13 Kevin Anderson; and 11th-seeded Milos Raonic pull a mild upset by beating sixth-seeded Nicolas Almagro 6-3, 6-3.
Nadal goes against Tipsarevic and Verdasco plays Nishikori in Friday quarterfinals in the same half of the draw. The other matches have Murray facing Raonic and Ferrer taking on Lopez.