The Queenslander had the chance to seal Australia's Fed Cup semi-final against Belarus on Sunday but was blown away by former world No.1 Victoria Azarenka 6-1 6-1.

The loss forced their Brisbane tie into a deciding fifth doubles rubber.

Australian captain Alicia Molik backed the former doubles No.1 and current Australian Open champion and Stosur delivered with Ashleigh Barty in a 7-5 3-6 6-2 triumph.

"Don't get me started," she said, holding back more tears.

"I'm very, very happy, very pleased. It was super exciting to bounce back and come out and play as well as what we did together ... it was just incredible."

Stosur, now 8-0 in Fed Cup doubles, rattled off two other tight doubles victories among a US Open singles title and French Open final appearance but said Sunday's win on her home court "was up there".

Molik said Stosur's performance spoke revealed plenty about her character.

"I didn't have any reservations ... listening during the warm up, multiple grand slam champion, No.1 in the world ... Sam's experience always shines through," she said.

"Today outlines there's not many athletes who can come back from a defeat in singles - we're talking about a 15-20 minute turnaround - to get yourself up, not everyone can do that."

Australian Associated Press