Murray cruised past Roberto Bautista Agut of Spain on Centre Court last night to finish the first week of Wimbledon with a record of three matches played, no sets dropped.
The 27-year-old Scot raced to a 6-2, 6-3, 6-2 win in one hour and 35 minutes and will play Kevin Anderson of South Africa, the 20th seed, on Monday.
"I am very happy with my game,"said the Wimbledon champion after a week that has witnessed his demolition of David Goffin, Blaz Rola and now Bautista Agut. "I have played well in all the matches."
Murray had back surgery in September but has been moving fluently this week. "I'm happy with where my body's at right now," he said. "Physically I feel good. My back feels much better than it did at this stage last year."
He said of a smooth first week at Wimbledon: "I have played well from the first game of the first match pretty much through until the end of today's one. I haven't used up too much energy, which is good."
Of Anderson, who stands 6ft 8ins and serves with venomous power, Murray said: "It will be a tough match. He's a big guy with a big game. It's probably been his best year on the tour so far in terms of consistency. It will be tough. He serves well, so I'll need to have my return game on."