The 26-year-old British number one endured a disappointing second half to the past year as she slipped from fourth in the world rankings to ninth having gone on a five-match losing streak stretching back from her last win at the Cincinnati Open in August.
Konta also dropped the first set in her first round match against American Maidson Keys on Monday, and was similarly pegged back by a big-hitting Tomljanovic in the opening set.
Tomljanovic, who had her boyfriend Nick Kyrgios watching on the side, broke Konta's serve four times, meaning when she held for just the second time herself, it was enough to take the first set.More news: EPS for JetBlue Airways Corporation (JBLU) Expected At $0.32
Konta, who overcame local hope Ajla Tomljanovic 4-6, 6-1, 6-4 in two hours and 26 minutes at the Pat Rafter Arena, set up a meeting with the victor of the match between Ukraine's Elina Svitolina and Croatia's Ana Konjuh.
"It was a tough match, Ajla came out playing well in that first set, she made it very hard", Konta, who will face either Ana Konjuh or third seed Elina Svitolina next, said in an on-court interview.
But then Konta kicked in to gear, finding her range on serve while still causing damage on her opponent's, and won the second set 6-1.More news: Democrat Jones officially declared victor over Roy Moore
Heather Watson was a late addition to the singles draw as a lucky loser, following the withdrawal of Petra Kvitova with a virus, but Watson was thrashed 6-0 6-3 by Anett Kontaveit of Estonia after previously failing to make it through qualifying.
And it was a similar story at Pat Rafter Arena on Tuesday, the fifth seed overcoming Ajla Tomljanovic, a Croatian-born, naturalised Australian, 4-6 6-1 6-4 in two hours and 28 minutes.
"There wasn't a lot in it but I am very happy to get through that".More news: MGM Resorts International (NYSE:MGM) Director Sean Charland Buys 25000 Shares