A day after Rafael Nadal exited the Madrid Masters and vowed never to return while the clay is still blue , a similarly disgruntled Novak Djokovic suffered a shock 7-6 ( 2 ) , 6-3 loss to fellow Serb Janko Tipsarevic . The world No . 1 said he would join Nadal in boycotting the Madrid tournament next year if organizers did not restore standard red clay to the courts . `` I want to forget this week as soon as possible and move on to the real clay courts , '' Djokovic said . `` It took me at least a week to try to get used to this surface and somehow find a way to win matches and play a decent level of tennis . `` There is no discussion in my eyes , it 's very simple . No blue clay for me . '' Nadal lost to fellow Spaniard Fernando Verdasco on Thursday for his earliest exit in a clay-court tournament in eight years . Verdasco was routed 6-1 , 6-2 by Tomas Berdych in Friday 's quarterfinals . The blue clay is the brainchild of tournament owner Ion Tiriac , who claims it helps fans see the ball and creates a better viewing experience . And while Djokovic and Nadal have crashed out , Roger Federer has thrived at the tournament , beating David Ferrer 6-4 , 6-4 on Friday to advance to the semifinals . The 16-time Grand Slam champion , president of the ATP Players ' Council , said he sympathized with Nadal and Djokovic . `` Yes of course , I said it from the start . It 's not something we actually wanted , '' he said . `` I understand their frustrations . It 's a bit tricky for everyone and we definitely have to look into things for next year . '' Federer will replace Nadal at No . 2 in the rankings if he wins the tournament , thereby increasing his chances of being seeded second for the French Open . Federer , who did n't face a single break point against Ferrer , will play Tipsarevic in the semifinals , while Juan Martin del Potro meets Berdych in the other after a comfortable 6-3 , 6-4 win over Alexandr Dolgopolov . Serena Williams , too , has been in blistering form in Madrid and won a battle of former No . 1s in typically ruthless style , thrashing Maria Sharapova 6-1 , 6-3 . Both players were unbeaten on clay coming into the match , but Williams extended her winning streak over the Russian to seven while winning her 10th straight match . Williams said the clay was `` extremely slippery '' but she would n't join the top men 's stars in skipping Madrid next year . `` If I 'm not here next year , it wo n't be because of the clay , '' said the 13-time Grand Slam champion . `` I do n't think there 's been any improvement in the courts over the week , but every clay court is different . `` This is not the best court -- definitely not what they play like at Roland Garros -- but it 's what they use at Madrid . '' Williams will face Lucie Hradecka for a place in the final after the Czech qualifier upset fifth-seeded Sam Stosur 7-6 ( 8 ) , 7-6 ( 6 ) . World No . 1 Victoria Azarenka avoided another upset when she recovered to beat French Open champion Li Na 3-6 , 6-3 , 6-3 . She will play Agnieszka Radwanska for the sixth time this year in Saturday 's semifinals , and said any complaints about the courts would have to wait . `` I 'm not a fan of this court , that 's for sure , '' she added . `` But I do n't want to sit here and complain about it . `` Nothing is going to change this year . We can talk after the tournament about possible changes . ''
Novak Djokovic loses 7-6 ( 2 ) , 6-3 to Janko Tipsarevic in Madrid . - The US Open is won by Roger Federer over Rafael Nadal in straight sets. Nadal said he would also boycott the event after his loss a day earlier . Roger Federer , Serena Williams and Victoria Azarenka all through to semifinals .