The Bulls' Champions Cup last 16 trip to Toulouse on Sunday will have additional significance for the French club's Springboks loose-forward Rynhardt Elstadt.
The 33-year-old spent seven seasons at the Pretoria-based outfit's fiercest opponents the Stormers before heading to the Top 14 giants in 2017.
The Bulls and the Stormers have met in various guises for almost a century with countless Currie Cup titles between them.
"They used to be my big rivals back home," Elstadt told AFP.
"It's always a dog fight. I'm looking forward to the challenge and I'm sure they're also looking forward to playing one of the really good sides in France," he added.
Stormers and Bulls have both reached the Champions Cup knock-outs in South African sides' first participation in the competition.
The two teams, as well as the Sharks and Lions, moved to the United Rugby Championship after more than 20 years in Super Rugby, facing franchises from the likes of New Zealand and Australia.
"I think logistic-wise for South African teams travelling up north is much easier," Elstadt said.
"We were used to travelling 10 or 12 hours, it was a bit difficult."
"To mix the southern and the northern hemispheres is good for rugby in general," he added.
HOMEWORK
Elstadt made the last of his four Springboks appearances in July.
He missed out on selection for the successful 2019 Rugby World Cup campaign but is eyeing this year's tournament which starts in September.
"I'm a bit older now, but I've always got the ambition of playing with the Springboks, especially in the World Cup," he said.
"It's every player's ambition."
"If I do get the opportunity to join the Springboks, it would be phenomenal, especially when it's in France," he added.
This weekend, record five-time European champions Toulouse will welcome back a host of their France Six Nations squad members including Antoine Dupont and Romain Ntamack who were both rested for last Saturday's Top 14 defeat to Castres.
Les Bleus, with half-backs Dupont and Ntamack, could face the Boks at the quarterfinals of the World Cup.
"I'm sure the French will try to do their homework on South African teams and players," said Elstadt, a 2021 Champions Cup winner with Toulouse.
"Especially when they play in France, to see which style they'll play against French teams and try to adapt that for the World Cup."
Elsewhere, the Stormers host Harlequins, titleholders La Rochelle welcome Gloucester and Leicester, European champions in 2001 and 2002, host Edinburgh.
There is also an Irish derby to savour as 1999 European champions Ulster head to Dublin to face four-time winners Leinster.