They've been arriving in their thousands this week, swelling Durban's 3 million population by up to 40,000. They have already made their presence felt around the city with their good humour and singing, but when the first Test kicks-off this afternoon they are going to join forces in a way only Lions fans can.
The Lions players know the atmosphere is going to be very special at the 52,000 capacity ABSA Stadium, but the fans are intent on turning it into a 'home' fixture for the team that only ever plays on the road.
The Lions licensed four Official Tour Operators to conduct the great air lift and the numbers who have taken up the packages on offer have increased on the last two tours.
In 2001, there were 20,000 officially packaged and independent travelling fans from the UK and Ireland who headed to Australia. Four years later those numbers had grown to 35,000 for the trip to New Zealand.
This week thousands of fans have been arriving daily in Durban and it is anticipated that between 30-40,000 will have joined the six week tour, with the majority of them converging on Durban for the vital first Test.
It has been a huge logistical exercise, and one that has been two years in the planning, but Justin Hopwood, of the Mike Burton Group, who are managing the official travel and hospitality programme for the British & Irish Lions, has been pleased with the response.
"The tour has now reached its peak with fans travelling and arriving into South Africa ahead of the first test match. Supporters have been planning this for years, some since the day after the last tour in 2005. Other have decided to get out to South Africa after the watching the team in the tour to date," he said.
"There are four Official Licensed Operators who have been selling official ticket-inclusive supporter packages, and the majority of their clients are arriving ahead of Saturday's fixture and some next week for the final two tests.
"The financial situation since September/October last year hasn't dampened the enthusiasm or the commitment of a true rugby fan wanting to experience the Lions in South Africa.
"This tour to South Africa is so special as the Lions are taking on the World champions in a similar situation to 1997. The next two tours in Australia and New Zealand are long haul, but some fans have been able to book a long weekend away for this one.
"The economy and everyone's personal financial situation has changed the way people are doing the tour - but not how many are doing it. For example, England Rugby Travel had 4,500 advance registrations from people who paid to get on the waiting list before it launched its packages back in June 2008 - that is the kind of enthusiasm there is for the Lions tour.
"Gerald Davies always calls it rugby's last great adventure. The fact the Lions is once every four years, and once every 12 years in South Africa, delivers a unique sporting occasion. The fans going over there have illustrated that."
Durban has never seen anything quite like it - and the Springboks are going to run out onto their own pitch and see a sea of red and hear fans from four nations singing their hearts out for one team.