Complex sentence: Kvitová's breakthrough season in 2011 began with a title in Brisbane and her first quarterfinal apperance at the Australian Open, where she lost in straight sets to then world no.2, Vera Zvonareva.
Split into simpler sentences: Kvitová's breakthrough season of 2011 began with a title in Brisbane. Then, she reached her first Australian Open quarterfinal but lost in straight sets to then world no.2, Vera Zvonareva.