At the 2008 Australian Open, Tošić was defeated in the first round by the eventual champion, Maria Sharapova, in straight sets.

[3] Playing for Croatia Fed Cup team, Kostanić Tošić has a win–loss record of 19–20.

She was eventually coached by Alan Maric; off-court trainer was Slaven Hrvoj.

Father Slobodan is an external bank auditor; mother Smiljana is a dental nurse; sister Marina is a student of economics.

Entire family plays recreational tennis on private court.