( CNN ) -- A mystery stomach bug is striking down men 's and women 's players at the Indian Wells Masters tennis event , but former world No . 1 Roger Federer shook off illness to cruise to victory in his opening match . Federer , a three-time winner of the U.S. hard-court tournament , has been suffering with flu-like symptoms but breezed past Ukraine-born American wildcard entrant Denis Kudla on Sunday . The third-ranked Swiss won 6-4 6-1 in 57 minutes to set up a third-round clash with Canadian rising star Milos Raonic . The 16-time grand slam winner was one several players to fall sick at the California event , but Federer managed to avoid the intestinal illness which forced some of them to withdraw on Sunday . France 's world No . 14 Gael Monfils and Austrian Jurgen Melzer were lost from the men 's draw , while ninth-ranked Russian Vera Zvonareva and American Vania King pulled out of the women 's tournament . Philipp Kohlschreiber , Andreas Seppi and Magdalena Rybarikova had earlier withdrawn . `` We 're fighting something of our own in our family , '' Federer , who has twin girls , told reporters . `` We have tons of stuff going on at the moment . `` I have a bit of a combination . Not terrible temperature , but I have some things going on . But I 'm the best off of the family , so thank God I 'm the tennis player here . No , the rest of them are struggling much more . '' Raonic , winner of two ATP Tour titles this season and seeded 27th , advanced courtesy of a 6-4 6-2 win over Argentina 's world No . 38 Carlos Berlocq . World No . 2 Rafael Nadal was in similarly impressive form , brushing aside 78th-ranked Argentine Leonardo Mayer 6-1 6-3 in his first match since losing an epic Australian Open final to world No . 1 Novak Djokovic . Nadal is also participating in the doubles event and won his first-round match alongside compatriot Marc Lopez last week . `` It 's nice to be back playing at a very good level , '' said Nadal , a three-time winner of this event who lost in last year 's final to Djokovic . `` Winning is the most important thing . It 's not easy to be back after a while without competition , but I did really well . I started the match very focused , very aggressive . I 'm very happy about almost everything . '' Next up for the 10-time grand slam champion is 26th-seeded compatriot Marcel Granollers , who beat Germany 's former world No . 2 Tommy Haas 6-3 2-6 6-3 . On a day of withdrawals , French sixth seed Jo-Wilfried Tsonga advanced after compatriot Michael Llodra was forced to retire with a knee injury while trailing 4-1 in the first set of their match . World No . 41 Llodra has reportedly been slapped with a $ 2,500 fine for racially abusing a member of the crowd during his victory over Latvia 's Ernests Gulbis on Friday . Tsonga 's next opponent will be Czech 28th seed Radek Stepanek , who beat Belgium 's Xavier Malisse 6-2 6-1 . Argentine ninth seed Juan Martin del Potro beat Australian qualifier Marinko Matosevic 7-5 6-2 to continue his bid for a third title of 2012 . The 2009 U.S. Open champion will next play Spanish No . 19 Fernando Verdasco , who beat American Ryan Sweeting 6-2 6-2 . In the women 's draw , 2011 Wimbledon champion Petra Kvitova was shocked by American teenager Christina McHale , slipping to a 2-6 6-2 6-3 defeat in their third-round clash . `` She played very solid and did n't make any mistakes , so it was tough , '' world No . 3 Kvitova said of the 32nd seed . `` The first set was fine today . Next time I play against her I will have to play the game I played in the first set -- a better serve , not many double faults , play aggressive and go for the net . '' McHale , 19 , who is searching for her first WTA title , said : `` It took me a while to get used to her big shots , but I definitely got a lot more comfortable as the match went on . It was definitely one of my biggest wins . '' McHale will play 18th seed Angelique Kerber in the fourth round , after the German benefited from the withdrawal of King . World No . 1 Victoria Azarenka is safely through after a 6-1 6-2 victory over Russian 25th seed Svetlana Kuznetsova . The Australian Open champion 's next opponent will be 14th seed Julia Gorges , who beat Spain 's No . 24 Anabel Medina Garrigues . Chinese eighth seed Li Na beat compatriot Zheng Jie 6-1 6-3 , and the French Open champion will next play Czech Klara Zakopalova , who profited from Zvonareva 's withdrawal . Polish fifth seed Agnieszka Radwanska set up a clash with American wildcard Jamie Hampton by beating Italian 27th seed Flavia Pennetta 6-4 6-2 .
Rafael Nadal advances at the Australian Wells Masters despite suffering with illness . The 16-time grand slam winner beat Denis Kudla 6-4 6-1 to reach the third round . A stomach illness has ravaged the U.S. event , with four players forced to pull out last year 's . first seed Roger Federer wins his first singles match since the Australian Open to advance .