Andy Murray booked his place in the quarter-finals of Wimbledon without dropping a set as he saw off the challenge of giant South African Kevin Anderson.

After a flawless first week, this was certainly the defending champion's toughest test but he passed it with flying colours, saving a set point in the third-set tie-break to win 6-4 6-3 7-6 (8/6).

Murray, who is likely to next meet Queen's champion Grigor Dimitrov, had a minor blip early in the second set after the roof was closed but quickly adjusted to the indoor conditions.

The roof, which had been shut for most of the preceding match, opened before Murray and Anderson walked onto Centre Court.

That would no doubt have pleased the Scot, who prefers playing outdoors, particularly when his opponent is a big hitter like Anderson.

Murray's great supporter Sir Alex Ferguson watched on from the Royal Box while his mother Judy was also there from the start this time.

Murray had joked after Judy chose to watch his brother Jamie instead on Friday that he was overlooked as the number two son, but all eyes were on the Wimbledon champion this time.

He could not have had a better first week but this was expected to be a step up, with 6ft 8in Anderson ranked 18th and having the best season of his career.

Murray has had good success against big servers, his exceptional return game helping to blunt the weapon, and he immediately had a good read on Anderson's delivery.

In the third game he brought up three break points and took the third when he teased the South African into sending a backhand long.

Murray could not take a chance to make it 5-2 but was showing off his full repertoire of skills and converted his second set point when Anderson netted a backhand.

Murray had been particularly vocal after winning big points, no doubt aware of the importance of not giving Anderson a way back in.

Six break points went begging in the opening game of the second set but Murray kept forcing the issue and got his reward on the seventh when Anderson put a volley wide.

Drizzle began to fall and Murray complained about the slippery surface to the umpire, but it turned out to be in the third seed's interest to continue as he broke again to make it 3-0.

At that point the rain became heavier and play was suspended while the roof was shut again.

Murray made a bad start on the resumption, offering up his first two break points and losing the second when Anderson's shot clipped the top of the net.

The Scot had a chance to restore his double break immediately but missed it and the match threatened to turn on its head when Anderson had a point for 3-3.

Murray saved it, though, and from 30-0 on the Anderson serve in the ninth game, he played four excellent points and won the set when he forced the South African to volley wide.

Anderson had shown throughout that he was far more than just a big serve, his movement mightily impressive for such a tall man.

He withstood five break points in the eighth game of the third set - Murray took just four of 19 chances in the match - and held on to force a tie-break.

Murray was two points away after a sublime forehand pass made it 5-3 but a 74mph second serve was punished and Anderson brought up the first set point with an ace.

Murray saved it with a fine serve of his own and then created a first match point, which he took thanks to two superb backhands after two hours and 33 minutes.

ends