Dominika Cibulková
She also won the WTA Finals in 2016 , becoming the fourth player ( after Serena Williams in 2001 , Maria Sharapova in 2004 and Petra Kvitová in 2011 ) to win the tournament on debut . 
<triplet> Maria Sharapova <subj> 2001 <obj> work period (start) <triplet> 2004 <subj> WTA Finals <obj> instance of