LONDON- Rafa Nadal may have left the stage but the smooth progress into Wimbledon's second week of the remaining members of tennis's established powerbase suggests further upsets are unlikely in the men's last 16 on Monday.

The 'Big Four' have been whittled down to a top three, but for Novak Djokovic , Roger Federer and Andy Murray , who were largely untroubled in their opening matches, there seems no end on the horizon to their dominance at the All England Club.

The trio, along with Nadal, have had a monopoly on the Wimbledon title after Lleyton Hewitt beat David Nalbandian to lift the Challenge Cup trophy in 2002.

On the evidence of the first week, only Stan Wawrinka, winner of two of the last six majors including last month's French Open, looks capable of stealing a march on the top three. The hard work of maintaining promising starts, however, is likely to begin with more testing encounters on Monday.

The relentless retriever Djokovic faces the towering figure of Kevin Anderson, Federer's quest for a record eighth Wimbledon title continues against Spaniard Roberto Bautista Agut and Murray faces the huge-serving Ivo Karlovic.

Having cruised into the last 16 without dropping a set, world number one Djokovic's renowned return will be tested by the serving of Anderson, whose recent form has prompted a surge up the rankings to a career-high 14.

"I think he is probably playing the tennis of his life all in all," Djokovic said of the South African after easing past Bernard Tomic in the third round.

The Serb's elastic-limbed defence has been untroubled in his three opening skirmishes, yet Anderson has weapons and can test the best if they are not on their game.