Should the scores be level after the reverse singles, Barty will partner Samantha Stosur to face Mladenovic and Garcia in a deciding doubles rubber.
Barty delivered a masterclass under pressure on Saturday, needing less than an hour to dispatch former world No.4 Garcia 6-0, 6-0.
The result evened the ledger after Mladenovic drew first blood for France with a 6-1, 6-1 routing of nerve-rattled Fed Cup debutant Tomljanovic.
Mladenovic was the last player to beat Barty before Australia’s spearhead embarked on a 15-match winning streak in Europe that culminated in French Open glory.
One of just 11 players to defeat Barty in singles in 2019, world No.40 Mladenovic utilised her lethal forehand to devastating effect in Saturday’s win over Tomljanovic.
But it will take something special from the Frenchwoman to defeat Barty after the Australian’s awe-inspiring performance against Garcia.
Barty said she had learned plenty about her French opponent from the 6-2, 6-3 defeat on clay six months ago in Rome.
“Having played her in Rome earlier this year, I know that she has the weapons to be able to make me uncomfortable,” Barty said.
“So it’s about trying to nullify those as best as I can and bringing it back to my tempo of match.
“I feel that I’ve changed and developed as a person and player since that match in Rome.
“I’m really looking forward to it tomorrow to try and turn the tide a bit.”