Weak results in Kambah and Curtin's polling places drove the Liberals' disappointing showing in two electorates the party was hoping would propel it to victory on Saturday.
Results showed the Liberals fell behind Labor across southern and western suburbs it hoped would deliver it numbers needed to form government.
A 3.9 per cent swing against the Liberals and a 7.4 per cent positive change for ACT Labor made the southern Brindabella electorate a decisive factor in the 2020 election result.
In the southern suburbs, thought of as a Liberal stronghold, the party had some of its worst results in Kambah South's polling location while Fadden gave it strongest support.
Labor polled best in Kambah South while the Greens' strongest vote in the electorate came in Kambah West.
Part of Kambah was moved into the Brindabella electorate following a boundary change before the election.
Strong results for Labor in Weston Creek and the Greens in Woden, and a weaker showing for the Liberals in Curtin, thwarted the opposition's attempts to take an extra seat in the Murrumbidgee electorate also seen as necessary for its narrow path to majority government.
Canberra Liberal candidate Andrew Wall, who lost his Brindabella seat, said the party may not have been as focused on the electorate as it should have been.
"We thought we had the upper hand in Brindabella having three incumbents running and for all intents and purposes three very good campaigns by the incumbents, and very good campaigns by James [Daniels] and Jane [Hiatt] as the other two candidates," he said.
Mr Wall said Kambah was always going to be uncharted for candidates in the 2020 election.
"It hasn't been part of the Brindabella electorate since the 2012 election so there was really no incumbent member for that area, and given it's only half of Kambah it's still a very broad, diverse suburb," he said.
"You could say it's representative of Canberra in itself. I'd say the result in Kambah mirrors largely what we've seen in many other parts of the city."