Petra is choking. Azarenka has the ability to just pull away with this match due to Petra playing like shit. Pironkova wasn't good enough or offensive enough to take advantage of the choke.
Petra is the better player, but this is your typical WTA choke job. Win the first set easily and then lose the next two
Petra is the better player, but this is your typical WTA choke job. Win the first set easily and then lose the next two