Just two teams have won three-test rugby series in South Africa: New Zealand and the British and Irish Lions.
A place in a fairly exclusive club awaits Ireland over the next two Saturdays if it can produce one more upset win over the Springboks.
As upsets go, Ireland's 26-20 victory in the first test in Cape Town rates highly.
Missing enough regulars to have to field a makeshift backline, and down to 14 men after 20 minutes with flanker CJ Stander's red card, Ireland stunned its doubters at Newlands last week, and just about everyone else, to win a test in South Africa for the first time.
In the second game in Johannesburg, and again in the final test in Port Elizabeth next weekend, Ireland's tourists have a chance at a much larger slice of history.
"Obviously it's a very special win," Ireland captain Rory Best said as the dust settled on the first test. "I suppose you'll see over the next two weeks just how special it is."
Best said Ireland's challenge now was to make sure that the Newlands game wasn't a "one-off," and coach Joe Schmidt warned of the danger of getting "too carried away."
"We're incredibly excited by the little bit of history, the small steps," Schmidt said, "but ..."
The "but" for Ireland is this: Rarely have the Springboks, slated by media and fans for their insipid first-test performance, been so desperate for a pride-restoring win.
"This is hurting as a player, as a Springbok," new captain Adriaan Strauss said.
And Johannesburg's Ellis Park is a ground where South Africa's fiercely physical style is always cranked up a notch or two anyway. Ireland appears set for a ferocious backlash from South Africa on Saturday.
With that in mind, Schmidt denied that the five changes he made to his team for Ellis Park was him conceding the second test and keeping something in reserve for a series-decider in Port Elizabeth. He called that an "insult" to the players he called in.
"I think it's important that we don't wait, that we try to grasp the moment that we can, and that moment is this weekend's game at Ellis Park," Schmidt said.
One of Schmidt's changes, no matter the reason, will spice things up.
South Africa-born Quinn Roux, who originally hails from up the road in Pretoria, will make his Ireland debut in Johannesburg in the second row. That will ensure there's at least one man playing against his country of birth after Stander, another of Ireland's three South African-born players on the tour, was suspended for the second test for his red card.
For the Springboks and new coach Allister Coetzee, there's grinding pressure after just one game of his reign. But Coetzee stayed true to his word that he believed in giving players an opportunity to "redeem themselves." Coetzee made just two changes, both forced by injury, to his starting team for the second test.
"We spoke hard," Coetzee said about the 1st test, adding that discussion of the team's performance had been "very frank."