Stosur produced a lacklustre and error-strewn performance to lose her semi-final 6-3, 6-2 to Czech world No. 37 Klara Zakopalova.
Just hours before their match, the pair were drawn to meet again at the Open in Melbourne after it gets underway on Monday.
Stosur can now boast only a 3-2 record over veteran Zakopalova, the seventh seed in Hobart.
Even if she can get past the 31-year-old at Melbourne Park, she could then face tough matches against Sydney finalist Tsvetana Pironkova and former world No. 1 Ana Ivanovic.
In a rocky start to her season, which began with a winless Hopman Cup campaign, Stosur has three wins from seven matches.
There was a bizarre start to Stosur's first semi-final on home soil since 2005, the world No. 17 needing a medical timeout after the warm-up when she suffered a bleeding nose.
The 29-year-old laughed as she had her blood pressure taken by the tournament doctor, eventually taking the court after a delay of around 10 minutes.
Stosur lost her opening service game but broke back immediately.
Zakopalova broke again in the sixth to lead 4-2 and then saved seven break points in the next game as the Australian attacked.
Surviving that onslaught, the Czech served out the set.
Stosur found herself down an early break again in the second but broke back for 2-2.
She meekly lost her next service game to love and was broken again for 5-2 before
Zakopalova served out the match.
Zakopalova will play the winner of the other semi between Spaniards Garbine Muguruza and Estrella Cabeza Candela in Saturday's final.