LONDON - Defending champion Andy Murray's tranquil progress through Wimbledon's opening week has been eerily calm. No pesky upstarts trying to knock him off his perch, no tumbles on the lush lawns, no niggles from the back that needed surgery last year and no question marks about his form which, for the first three rounds, has been imperious.

So straightforward were his victories over David Goffin, Blaz Rola and Roberto Bautista Agut, during which he dropped a total of 19 games, that post-match news conferences have resembled friendly chats about everything from rescuing stray dogs to favourite vacations and the World Cup soccer in Brazil.

As grand slam tournaments go, it has all been a breeze. After the calm there often follows a storm, however, and with a second successive title only four victories away Murray and his fans will be scanning the horizon for looming dangers. Rewind 12 months and it was a similar story. Then, the Briton was untroubled until the quarter-finals when his quest to become the first home player to win the men's singles for 77 years turned into a white-knuckle ride.

First he had to come from two sets down against Spain's Fernando Verdasco and then he was in a heap of trouble against powerhouse Pole Jerzy Janowicz before reaching the final where he beat Novak Djokovic in three memorable sets. Things could get more tricky when Murray faces big-serving South African Kevin Anderson in the last 16 on Monday.

Anderson, seeded 20, has belted 63 aces in three rounds and while his serve is his big weapon he is also more than capable off the ground. World number five Murray knows his first big test is around the corner. "I haven't used up too much energy which is good," said the Scot who will feature in the second match on Centre Court on Monday. "It will be a tough match," Murray told reporters. "He's a big guy with a big game. He's played some very good tennis this year. "It's probably been his best year on the tour so far in terms of consistency. I'll need to play a tough match to beat him."

Should he win, Murray could then come up against tournament dark horse Grigor Dimitrov who has continued the form that saw him win the warmup event at nearby Queen's Club.

The Bulgarian plays rising Argentine Leonardo Mayer next. Unlike the women's draw, most of the men's title contenders are still up and running with the exception of Czech former runner-up Tomas Berdych. Top seed Novak Djokovic will hope he has no lingering effects from the shoulder he hurt diving for a forehand against Gilles Simon in Friday's third round.

The Serb faces the dangerous Jo-Wilfried Tsonga, the player he beat in the semi-finals on the way to the 2011 title, in the pick of the last 16 matches. "For me the goal will be to make my dance at the end," said Tsonga who is well known for his victory celebrations. World number one Rafael Nadal has had the toughest first week of the so-called "big four", dropping the opening set in each of his matches.

However, in winning the final three sets against Mikhail Kukushkin 6-1 6-1 6-1 on Saturday the Spaniard looked to have played himself right back into his best grasscourt form. The 28-year-old will play Australia's 19-year-old wildcard Nick Kyrgios in an intriguing fourth-round clash.

"Young players are very dangerous, they have something special and they are able to play with no pressure," said Nadal who is bidding for his third Wimbledon title. Kyrgios, the sensation of the tournament so far, says the meeting with Nadal in his first Wimbledon is beyond his wildest dreams. "I never thought I would be seeing Nadal in the fourth round in my 19th year," he said. "I thought it would take years and years of work to finally have an opportunity like that. To think that it's going to happen is daunting but so exciting as well."

Roger Federer can never really be "under the radar" at Wimbledon, such is his popularity, but he has gone about his business with the minimum of fuss and looks to be in fine fettle ahead of his last 16 showdown with Tommy Robredo. The two 32-year-olds played at the U.S. Open last year when Robredo dished out a three-set beating and Federer will no doubt have that on his mind as he bids for a last-eight spot.

Monday's schedule will have a rather muddled look with two third round matches, Stanislas Wawrinka v Denis Istomin and Feliciano Lopez v John Isner, yet to start because of heavy rain that fell on Saturday. The weather forecast for the second week is fair and the action is sure to hot up.