A blue-ribbon Liberal seat in Melbourne’s affluent inner eastern suburbs is under threat from a surprising front – The Greens.

The once-solid seat of Higgins, the well-heeled felectorate of former treasurer Peter Costello, is at serious risk of falling to the Greens, according to that party’s polling.

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Polling commissioned by the Greens in early June showed their candidate Jason Ball on a primary vote of 24.1 per cent, while incumbent Kelly O’Dwyer’s vote has slumped to 44.1 per cent.

If Mr Ball picks up preferences from Labor it could be enough to topple Ms O’Dwyer in Higgins.

“We have turned a safe Liberal seat into a marginal seat,” Mr Ball proclaimed on Tuesday.

One Liberal source told Fairfax Media that Higgins could become the “Indi of 2016”, referring to the shock loss of the northern Victorian seat in the 2013 election by then-Cabinet minister Sophie Mirabella.

The poll was reportedly conducted three weeks after Ms O’Dwyer made a headline-making gaffe over a “$6000 toaster” when she appeared on the ABC’s Q&A program.

Last week, Prime Minister Malcolm Turnbull spent valuable time campaigning in the Liberal seat that has never gone to preferences since its creation in 1949.

Now we know why.

Mr Turnbull visited Higgins where he made a minor funding commitment for new netball courts.

Standing next to him were Ms O’Dwyer and professional netballer Jo Weston, who he described as role models for the student audience he was addressing.

“What they show you is that you can do anything,” the prime minister told them.

“You can play for Australia you can be a cabinet minister.”

Ms O’Dwyer will be hoping that holds true after July 2.

– with AAP