Andy Murray progressed to the quarter-finals of the Qatar Open in Doha with a comfortable 6-2, 6-4 victory over Philipp Petzschner, of Germany.

The 2008 US Open finalist was rarely troubled as he remained on course to defend his title and continue his encouraging build-up to the Australian Open, which takes place later this month.

Murray claimed the first break of serve in the third game after unsettling Petzschner with some determined defence.

The key breakthrough, though, came when a Murray set up break-point with his signature drop shot. A Petzschner lob then went long and the Scot held for a 3-1 lead.

Petzschner, 24, threatened at times on his forehand from the baseline, but Murray extended his advantage to 5-2 with a break in the seventh game and took the set on his second set-point when a Petzschner backhand landed wide.

The world No 66 then meekly surrendered his serve to love in game three of the second set, Murray claiming a 2-1 lead as the German sent a forehand long to compound a series of unforced errors that started with a double-fault.

Murray moved 3-1 ahead by holding in game four and served out the match in the tenth game, claiming the second of three match points.