Injury was the only reason Serena didn't win the Aussie Open. Injury and illness were why she didn't win Doha. And injury today was the only reason Li Na was even in that second set. Serena really should be undefeated this year and about to win her 4th title in 4 tournaments.
It's still a continuation of last summer. She remains far superior to everybody else and nobody is in her zip code. Her health is going to dictate what happens in every tournament she enters in 2013.(Of course, players need to take advantage of tourneys she doesn't play) If she's close to 100%, she's going to win all the big ones. If she's hampered by something, the door opens slightly for Maria, Vika, Na, Petra, Agi, and maybe a few others to vulture whatever titles they can. And Azarenka already did just that in Melbourne and Qatar. Maria did that at IW. Pounce when you can.