Novak Djokovic and Andy Murray edged closer to an epic Wimbledon final showdown while Poland played Grand Slam gatecrashers by guaranteeing at least a semi-final spot.
World number one Djokovic, the 2011 champion, dropped his serve for the first time at this year's tournament before beating Tommy Haas, the 35-year-old German 13th seed, 6-1, 6-4, 7-6 (7/4) in the fourth round.
Djokovic will be playing in his 17th successive Grand Slam quarter-final where he will face Tomas Berdych, the seventh seed and 2010 runner-up, who beat Australia's Bernard Tomic, 7-6 (7/4), 6-7 (5/7), 6-4, 6-4.
Djokovic boasts a 13-2 career record over Berdych but lost to him at Wimbledon in 2010.
"Haas is always a tough opponent. I had lost to him twice on grass before. He has great variety in his game and I always knew it would be a tough challenge," said Djokovic, who fired 13 aces and 40 winners.
"It was never going to be easy. I had to work for my games but I served well and returned well. I am happy to have closed it out in straight sets.
"I am playing really good tennis now, maybe even better than when I won the title in 2011."
Second seed Murray took another step closer to ending Britain's agonising 77-year wait for a men's champion when he survived a second set wobble to carve out a 6-4, 7-6 (7/5), 6-1 win over Russian 20th seed Mikhail Youzhny.
Murray, the runner-up to Roger Federer in 2012, will face Spain's Fernando Verdasco for a place in the semi-finals.
The Scot has an 8-1 winning record over unseeded Verdasco, a former top-10 player.
Murray had to battle back from 2-5 down in the second set to quell the threat posed by Youzhny, who needed treatment on a shoulder injury after one game of the third set.
Murray put in an impressive serving performance, firing 15 aces and hitting 45 winners past the experienced Russian.
