Dokic, who reached the quarterfinals at the Australian Open last week in her first Grand Slam appearance in three years, beat Thailand's Suchanan Vitraprasert 6-1, 6-2 to give Australia a 1-0 lead.
Samantha Stosur was down a set and trailed 2-5 before she broke Tamarine Tanasugarn's serve to spark an 11-game roll for a 4-6, 7-5, 6-0 win that gave Australia a winning 2-0 lead.
Casey Dellacqua and Rennae Stubbs combined to beat Noppawan Lertcheewakarn and Varatchaya Wongteanchai 6-4, 6-2. The Australians beat South Korea 3-0 to start the tournament and would have to lose every match against Taiwan on Friday to miss the final.
In the other Group B match, South Korea won both singles matches before Taiwan rallied to win the doubles.
In Group A, Indonesia had a 3-0 win over an India team missing star player Sania Mirza, who withdrew from the tournament with torn abdominal muscles.
New Zealand beat Uzbekistan 2-1 to remain unbeaten.
The top teams in each group will play a final to decide which country advances to the World Group II playoffs in April.
Dokic guides Australia to another Fed Cup win
Oliveira’s Debut Goal Helps Real Betis Beat Ten Man Sevilla
Exclusive: Indonesia - Hosting World Cup Is Not Impossible
