The pair will go head-to-head at the National Press Club in Canberra on Wednesday night, winding up another day on the campaign hustings.
The contest comes after the prime minister narrowly lost his second debate against Shorten in Brisbane on Friday, according to the undecided voters who attended.
He also lost their first bout by a greater margin in Perth at the start of the week.
Among the more memorable moments of the two exchanges came in Brisbane, where Shorten accused his opponent of being a “space invader” for getting close to him while asking about his tax plans, to gleeful applause.
Morrison has expressed no regrets about how he performed and has been happy to riff off the theme for his argument that Labor doesn’t have what it takes to manage the economy.
“The only space he’s going to invade is people’s wallets,” he told 2GB Radio about Shorten on Tuesday.
The debate looms after an eventful day on the trail for the prime minister on the border of NSW and Victoria.
An attempted egging at a Country Women’s Association meeting in Albury overshadowed a series of events at which Morrison wanted to focus on talking up his candidate for Indi Steve Martin and MP for Farrer Sussan Ley.
A young woman approached the prime minister from behind and threw an egg at him as he tried to leave the CWA gathering, surrounded by older women eager to speak with him.
It appeared to make contact with the back of his head before ricocheting off without breaking.
The 24-year-old Victorian is facing common assault and drug possession charges.
CWA member Margaret Baxter was also bowled over in the kerfuffle, with Morrison acknowledging her toughness after she found her feet.
“We’ve just got to disagree better about these things,” he later told reporters.
“Just because you have a difference of view to someone, doesn’t mean that you have to engage in these sorts of ugly types of protests.”
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