Australian Open champion Li Na advanced to the Madrid Open quarterfinals coming back from a set down, while two-time defending champion Serena Williams won more routinely on Thursday. After a poor opening set, the second-ranked Li overcame a slew of unforced errors and a bothersome toe problem to beat Sloane Stephens of the United States 2-6, 6-3, 6-2 on the clay at the Magic Box tennis center. ''After the first set I was like, 'calm down,''' said Li, who needed two hours to pull out the win. ''I say, 'OK, I cannot only think about what happened for the game, you have to look forward otherwise you cannot make it.''' Williams earned her 650th career victory with a 6-2, 6-3 win over Carla Suarez Navarro, who couldn't carry over the success of winning her first career title in Portugal on Saturday to the Spanish capital. More...