Scotland boss Gregor Townsend believes taking South Africa's scalp on Saturday will be a bigger achievement than this year's Calcutta Cup triumph over England.
The Dark Blues ended a decade-long wait for victory over the Auld Enemy when they defeated Eddie Jones' Red Rose at Murrayfield back in February.
It was just the second time England had tasted defeat in Jones' first 26 Tests in charge and for Townsend it was a feat which even edged last summer's shock win over Australia in Sydney.
But the head coach says his men will have to reach even loftier heights at Murrayfield on Saturday if they are to take down a Springboks side still buzzing from September's win over New Zealand.
Asked where a victory this weekend would rank from his 18 months in charge so far, Townsend said: "Given what South Africa have done recently, it would probably be our biggest win in the last couple of years.
"Obviously England stands out as such a memorable win. The fact they had won so many games in succession and that trophy we play for makes it even more special.
"But I just feel that South Africa are in the top two or three teams in the world with the way they play against the best teams in the world.
"Going to New Zealand and beating them, almost beating them a second time, showing what they were capable of last week against France as they came from behind to get a great win – that all shows they are going to be a tough team to beat."
Scotland had to maintain discipline and control last weekend as they neutered the livewire threat of Fiji before eventually dishing out a brutal eight-try lesson to the Pacific Islanders as their backs were let loose.
This time, however, Townsend is expecting a war of attrition that will push his players' mettle to the limit.
"It's the number-one physical challenge," he said. "We get physical challenges in the Six Nations with the likes of England and France and Ireland but any coach will tell you that the biggest physical challenge is South Africa. It always has been.
"They have evolved their game since Rassie Erasmus took over but they've not gone away from the forward pack. They select the biggest and strongest men they can find."
To combat that muscular threat, Townsend has made five changes to his pack, with prop Gordon Reid, hooker Stuart McInally, locks Jonny Gray and Ben Toolis returning alongside flanker Hamish Watson.
Centre Huw Jones is also trusted with a recall despite a couple of defensive slips in Cardiff a fortnight ago, while Stuart Hogg will make his first Scotland appearance since it was confirmed he will swap Glasgow for Exeter this summer.
Tuesday's announcement ends months of speculation about the full-back's future and Townsend is relieved.
He said: "We have known about it for a few weeks and it's great his future has been sorted – let's hope it's a good move.
"As much as we would have liked him to stay in Scotland, the best outcome is that he has at least made a decision now.
"He's going to a very good club. We have a lot of respect and admiration for what Exeter have done. They play excellent rugby and have a fantastic culture.
"It's important now that I now build a good relationship with Rob Baxter and the other coaches down there and we have Stuart's goals in mind of playing as well as he can for Exeter but also for Scotland."
