"I think a victory for the Lions would top everything," said Gatland, who played against and beat the Lions on their tour of New Zealand 16 years ago.
"It would be a huge achievement and for me personally it would be one of the biggest moments."
One of the major reasons why a series victory over the Boks would rank so highly for the 45-year-old is simply the difficulty of achieving such a substantial goal.
The Lions have arrived in South Africa as severe underdogs, having lost their previous two Test series' and been whitewashed by the All Blacks four years ago. To attempt to de-thrown the reigning world champions on South African soil is clearly a major task, and one that is not lost on Gatland and his fellow coaches.
"We are acutely aware of the enormity of the task of trying to beat the world champions in their own back yard," added Gatland.
"South Africa are always strong and tough and there is a huge amount of depth and talent in Springbok rugby.
"I don't think it matters what team they put out. They put that green jersey on and give everything for the cause - you don't expect anything less from not just the Test side, but any South African team.
"I can't speak highly enough of the respect I have for them. They are world champions - they've won the World Cup twice - and they are always incredibly motivated.
"But we can win. We have got players in this squad who have won on the big occasions. It is important you have a group of people who know what it is like to win when the pressure really comes on.
"There is no point coming out here if we don't believe we can do that. That is what sport is about - having those challenges which you try and overcome by going out there and trying to achieve something special."