Roger Federer has warned Novak Djokovic and Andy Murray it will take a huge effort to stop either him or Rafael Nadal winning yet another Wimbledon title.
The Australian Open champion Djokovic has made a powerful start to his bid for a first Wimbledon crown, while Murray's strong form has again encouraged British fans to tip him to end Britain's 75-year wait for a men's champion.
Federer a 16-time grand slam winner plays France's Jo-Wilfried Tsonga in the last eight and is seeded to play Djokovic in the semi-finals.
In the other half of the draw defending champion Nadal, who's appeared in four of the past five Wimbledon finals is seeded to meet Murray in the semis.
But Federer who has only missed one Wimbledon final in the past eight years believes it's too soon to talk of the old guard being unseated by Djokovic and Murray.
