( CNN ) -- A worrying back problem and the damp British weather were not enough to stop Roger Federer marching into a 33rd successive grand slam quarterfinal on Monday . The 16-time major winner kept alive his hopes of joining Pete Sampras on seven Wimbledon successes after beating another tennis veteran Xavier Malisse 7-6 ( 7-1 ) 6-1 4-6 6-3 for the 850th victory of his illustrious career . Federer , who had to come from two sets down to defeat fellow 30-year-old Julien Benneteau on Friday , needed to call for a medical timeout to receive painkillers at 4-3 up in the opener . `` I was in a lot of pain . The treatment and the painkillers worked . I started to feel better as the match went on , '' said the Swiss , who will next play another 30-year-old , Russian 26th seed Mikhail Youzhny . `` It was a shock for it to happen in the first set of a grand slam when you have to play five on grass . I thought I was in big trouble at 5-6 and he was serving for the first set . I apologized to Xavier for having to go off , but it was just a freak thing . '' The cool , wet conditions did n't help Federer 's back , but he said he was glad that the Centre Court roof was not closed before he completed his win over the Belgian . `` I was happy they kept it open because it is an outdoor tournament at the end of the day . We do n't want to play indoors all the time , '' he said after extending his record against 2002 semifinalist Malisse to 10-1 . `` It 's not that big of a deal coming on and off . To see the referee coming out and inspecting the courts , that 's the whole drama that belongs to Wimbledon . Eventually , if it 's too bad and it 's really raining , this is when you shut it . '' Youzhny had previously reached the fourth round on six occasions , including last year , but but went one step further this time as he beat Uzbekistan 's Denis Istomin in a five-set match lasting more than four hours . If third seed Federer gets past Youzhny , then he will next face world No . 1 Novak Djokovic , who beat fellow Serbian Viktor Troicki 6-3 6-1 6-3 on Centre Court later Monday . It was the friends ' first meeting on grass , but defending champion Djokovic had no problems posting his 12th successive win over the 34th-ranked Troicki -- who might be his doubles partner at the London Olympics -- to reach his 13th consecutive major quarterfinal . The 25-year-old will next face the winner of the match between French 18th seed Richard Gasquet or No . 31 Florian Mayer of Germany , who led 6-3 2-1 when play was halted earlier in the day on Court Three . British fourth seed Andy Murray had won the first set to lead his last-16 clash with Croatia 's Marin Cilic 7-5 3-1 when rain halted play on Court One , while France 's world No . 5 Jo-Wilfried Tsonga lost his opening set against Mardy Fish as the American led 6-4 1-1 on Court Two . The three delayed matches will resume on Tuesday , along with the two last-16 tiers that did not even start : Spanish seventh seed David Ferrer against Argentina 's No . 9 Juan Martin del Potro , and unseeded American Brian Baker versus No . 27 Philipp Kohlschreiber of Germany .
Two - time champion Roger Federer reaches quarterfinals with four - set win . Swiss world No . 3 has back injury and long delay on Centre Court . Federer will next play Russian 26th seed Mikhail Youzhny in grass - court event . He has a possible semifinal against world No . 1 Novak Djokovic .