The Liberal Party is battling to hold onto key seats in Melbourne's eastern suburbs, while Labor is edging ahead in a tough contest with the Greens for the inner-city electorate of Macnamara.
National swings away from the Coalition have been replicated in Victoria, helping Labor sweep to victory.
It is not yet clear whether Labor will get enough seats to form an outright majority or whether it will need to negotiate with a crossbench dominated by "teal" independents and Greens MPs.
A number of key Victorian seats may decide whether incoming Prime Minister Anthony Albanese will govern with a majority or minority government.
Menzies straddles the upper Yarra River and outer-eastern Melbourne suburbs such as Bulleen, Warrandyte, Doncaster, Donvale and Bulleen.
The electorate has only been held by two members since it was created in 1984 — former Liberal Party deputy leader Neil Brown and retiring MP Kevin Andrews, who was the MP since 1991.
Until this election, it had been considered a safe Liberal seat and was held by Mr Andrews on a comfortable 7 per cent margin at the last vote.
But a massive swing away from the Coalition meant Liberal candidate Keith Wolahan and Labor's Naomi Oakley were neck and neck when voting closed on Saturday night.
Eyes are also on Deakin, covering suburbs like Forest Hill, Vermont, Heathmont, Ringwood and Croydon.
As counting closed on Saturday night, the race between outgoing assistant treasurer and housing minister Michael Sukkar and Labor challenger Matt Gregg was too close to call.
The Liberal Party has also faced a swing against it in nearby Casey, which was vacated by outgoing Liberal MP Tony Smith.
With more than 70 per cent of the vote counted, Liberal candidate Aaron Violi was still on track to win the seat for his party.
Victorian seats where Labor lost ground to the Liberal Party on a two-party basis included Scullin, La Trobe and Holt, as well as the new seat of Hawke.
This is despite the Liberal Party seeing a reduced primary vote, instead making gains on preferences from minor parties including United Australia Party and One Nation.
Liberals lose key Victorian seats
The swing in Menzies is representative of the picture in other seats spanning formerly blue-blood Liberal heartland.
Menzies shares its western border with Kooyong, which the ABC has called as lost by outgoing treasurer Josh Frydenberg to independent "teal" challenger Monique Ryan. Mr Frydenberg has not officially conceded but acknowledged it would be "very, very difficult" to retain the seat.
The nearby seat of Higgins has also left Liberal hands for the first time since it was created in 1949, with infectious diseases physician Michelle Ananda-Rajah claiming victory for Labor over the Liberals' Katie Allen.
And in Goldstein, which takes in wealthy bayside suburbs like Brighton in Melbourne's south-east, another "teal" independent Zoe Daniel has claimed victory over Liberal Tim Wilson in a historic win.
Chisholm, which has changed hands between the Liberal and Labor parties over recent decades, has been comfortably won by Labor's Carina Garland.
Greens' primary vote picks up
Alongside the teal independents, the Australian Greens have been another clear winner of the 2022 vote.
Leader Adam Bandt has been comfortably returned to his seat of Melbourne.
The party is also hopeful of picking up another Lower House seat in Macnamara, which takes in inner-south-east Melbourne suburbs like Port Melbourne and St Kilda.
Labor's Josh Burns was ahead by more than 3 per cent when voting stopped on Saturday night, but the Greens' Steph Hodgins-May secured a more than 7 per cent increase in her party's primary vote in the seat.
In Melbourne's inner-north, Labor comfortably retained Cooper and Wills, but the Greens' primary vote picked up significantly in both those seats.
In the Queensland electorate of Ryan, which covers leafy western suburbs of Auchenflower, Indooroopilly and Ashgrove in Brisbane, the Greens' Elizabeth Watson-Brown has defeated Liberal Julian Simmonds.
The Greens' Max Chandler-Mather is ahead in Griffith and Stephen Bates is also in front in the seat of Brisbane.
