Remarkably, Tokyo Olympics 2020 will be the first Games where the five-time medallist will be absent from the rowing fray since Atlanta 1996.
The 45-year-old, now chair of UK Sport, believes her torch as Scottish standard bearer has passed to Swann who will begin her quest for pairs gold with Helen Glover on Saturday.
Glover, golden in the event in 2012 and 2016, has stolen the spotlight with her extraordinary return following the birth of three children and four years away.
But Swann, 33, also retired following silver from the eights in Rio to complete her medical degree and then a stint as a junior doctor in Livingston before immersing herself in the pursuit of what would be an incredible victory.
“Polly is such a brilliant story,” said Grainger. “She obviously had a great result in Rio, took time off to go back to Edinburgh University to complete her studying and then, work for the NHS through the pandemic. It is an incredible dual life.
“And during that time she thought, ‘I want to come back and have one more Games.' Now she's got a brilliant potential in a very fast pair with Helen Glover. All parts of Polly's story is inspiring to people.”
The rowing competition set to begin on Friday at Sea Forest Waterway, right beneath the busy and noisy flightpath into Haneda Airport.
All but three are Olympians for the very first time. Each one can be high-flyers, Grainger predicts, if they maintain their calm.
“We've always had a strong Scottish contingent. I do feel is a very big part of that comes from role models within sports, within teams. And I'm excited. We're in an interesting period now for rowing. I think there's even more to come in the next Olympics and beyond. And I think there'll be a few big new names coming along soon.
“I think it was Socrates originally who wrote Know Thyself. People are all different. And one of the biggest things I learnt was: there's no right or wrong to this stuff. Some people need to go to the Games feeling it's a big deal. 'I do need to feel this is the climax of my career. And this is the pinnacle of everything I'll do.' And that gets you ready.“Others need the reverse. To think, you know what, it's still the same 2000-metres rowing lake, or 100-metre sprint distance, 50-metre pool, whatever it is.
“This is still the same environment that I've been in for years. And the only difference is that the title we give it, and the standard of competition. Ultimately the rest of it is very controllable.”