Simona Halep in Sofia final
Ahead of Sunday's final, Stosur leads their matchup 3-2, but Halep has won twice this season. She won their recent Kremlin Cup final for her fifth title of the year. Stosur has two titles this year.
Ivanovic, a two-time winner of the tournament, led 3-0 in the third set before Halep won six consecutive games.
Stosur raced through her first set, but Pavlyuchenkova won six straight games to win the second. In the third, Stosur earned the only break and held on.