By Toby Davis
LONDON (Reuters) - 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 defense has been untroubled in his three opening skirmishes, yet Anderson has weapons and can test the best if they are not on their game.
Federer pulled out the party tricks in the opening week and laid down an early marker for the accolade of shot of the tournament with an outrageous lob from between his legs over Sam Querrey in his second round match.
Having followed that by taming the huge-serving Sam Groth in four sets, he heads into week two with the prospect of surpassing Pete Sampras and William Renshaw as the only man with eight Wimbledon titles looking plausible.
Not that the Swiss maestro is allowing himself to get excited about the possibility.
"This is more something like you talk about for a couple weeks, it's gone again, then you have to wait a year if you don't do it," he said.
Murray, champion in 2013, has suffered a couple of wobbles in matches against Mikhail Kukushkin and Andreas Seppi, but has looked comfortable enough not be unduly worried by 23rd seed Karlovic.
As for fourth seed Wawrinka, the Swiss has made a habit of scything through the early undergrowth of grand slams almost unnoticed and with his majestic backhand should have too much for Belgian David Goffin.
(Editing by Ken Ferris)