Murray has slipped out of the world's top 10 to number 11

It was his first match since missing Great Britain's Davis Cup tie with Argentina after being told swapping surfaces could aggravate a knee injury.

"The first set was very average but the second was much better," said Murray. "It comes and goes with my knee.

"There's pain with some movements but I have to live with it. I'd love to have a strong knee but it's not the case."

Murray, who used to share a flat with Huta Galung when they were both based in Spain, struggled to dominate the world number 190 at first.

After five straight breaks of serve the 20-year-old Scot held to win the first set.

606: DEBATE Your views on Murray v Huta Galung

In game eight of the second set he came back from 0-40 to win, then took the next two to set up a clash with Stanislas Wawrinka.

Murray's decision to miss the recent Davis Cup tie in Buenos Aires upset some of his team-mates, with brother Jamie saying at the time: "If he wanted to really push himself he could have come here."

Great Britain coach John Lloyd was only informed of his decision through a third party, but he insisted he took Murray at his word about the injury, and he still had a role to play in future Davis Cup teams.