The ABC is projecting Liberal MP James Stevens will retain the eastern Adelaide suburbs seat of Sturt.
Before the election, Sturt was considered a safe Liberal seat, with a 6.9 per cent margin, but is now down to 0.9 per cent.
Labor's Sonja Baram came close to winning the seat but posted on social media and congratulated Mr Stevens.
"I congratulate James Stevens on his re-election as the Member for Sturt and wish him all the best for the next term of Parliament," Ms Baram said.
"With 76% of the votes in Sturt counted, it’s becoming clearer that our campaign is likely to fall just short of victory.
"I want to offer my sincere thanks to every resident of Sturt, from Gilles Plains to Glenunga and from Norwood to Athelstone, who voted for me in this election.
"Back in February, we began our campaign in this blue-ribbon seat, held by the Liberals since 1972. We were the underdogs and faced an uphill battle from day one."
While Labor came close to winning, it was mostly through Greens preferences, with local candidate Kate McCusker gaining 15.8 per cent of the primary vote.
Before 2019, the seat was held by former defence minister Christopher Pyne, who barely held onto it at the 2007 election, when he also scraped across the line with a 0.9 per cent margin.
Mr Stevens, who once worked as former South Australian premier Steven Marshall's chief of staff, acknowledged the shift towards the Greens in his seat.
"Clearly what happened in Sturt was people who have voted Liberal in the past went to the Greens," Mr Stevens said.
"There was basically no swing to the Labor Party in my seat but the swing against me went to the Greens and that's a very clear message to myself but also to the Liberal Party."
Mr Stevens's win in Sturt means Boothby was the only seat to change hands in South Australia, with Louise Miller-Frost winning over Liberal candidate Rachel Swift.
