Li Na beats Zheng Jie to progress into last 16 in Madrid

Li Na beat fellow Chinese tennis player Zheng Jie 6-2, 6-3 to move into the last 16 of the WTA Madrid Open tennis tournament on Tuesday.

Li rarely looked in trouble and was more confident on her serve in the second set than she had been in her victory of Kristen Flipkens on Monday, when she had needed to win a second set tiebreak in order to ensure a straight set win.

Playing at mid-day for the second day in succession, Li was able to win her Tuesday match in one hour and 18 minutes.

The No. 2 seed will now meet No. 16 seed, Sloane Stephens, who needed three sets in order to defeat Petra Cetkovska 6-4, 2-6, 6-3.

The No. 8 seed Maria Sharapova suffered a real fright against Christina McHale: the Russian trailed by 4-1 in the decisive third set and looked to be crashing out of the competition, before digging deep to win the last five games and qualify 6-1, 4-6, 6-4.

Finally there was a disappointment for tennis fans on Tuesday when three times winner in Madrid, Roger Federer announced that he was withdrawing from the tournament because his wife was about to give birth.

"I've decided to withdraw from Madrid to be with my wife Mirka during these next few exciting weeks for our family. I apologize to my fans and hope to be back in Madrid next year. I'll be training near my home, and am excited to rejoin the Tour soon," announced Federer on his Facebook page.

Federer won in Madrid in 2006, 2009 and 2012 and his absence means fans will not be able to see him, not Novak Djokovich, who confirmed on Tuesday that he would not play in this year's edition as the result of a wrist injury.