I am starting to think that she won't win another slam. She has stumbled quite a few times in the later stages of finals recently, and she is also showing uncharacteristic vulnerabilities as in the first round here. The second set was easy, but the first really was not. I think the problem is mainly mental, but obviously with each tournament the physical side becomes harder as she nears retirement.
Serena Williams just gave up this morning due to an injury to the achilles tendon according to her words.