Critics provide Irish with the perfect Springbok motivation.
The former international lock forward knows the Irish are most comfortable in their traditional guise as underdogs and performances on tour so far have ensured they will start in that role again in Bloemfontein.
Only one win in four matches against provincial sides, including a 52-13 defeat against Griqualand West on Tuesday, have hardly left South African observers impressed with the visitors so far.
But both Lenihan and coach Warren Gatland are confident that the XV who face the world champions including British Lions hooker Keith Wood for the first time will be made of sterner stuff.
"Everyone here is writing us off and that is music to my ears," said Lenihan. "It is a great motivational opportunity and I believe we can surprise everyone.
"The way our midweek team has been playing has got nothing to do with the ability of the Test side.
"The Test side is very experienced and the more people believe we've got no chance the better it is for us," he said.
Kiwi coach Gatland, a man of few words, was equally dismissive of the impending gloom being heaped upon his side.
"I am here to win," he declared. "What else am I doing in South Africa?" His South African counterpart Nick Mallett, while admitting his side would be odds-on favourites, was also keen to play down expectations of a landslide victory for the Springboks.
Mallett cited the Irish performance in coming within minutes of upsetting France in Paris earlier this year as evidence of the task awaiting his own side.
"I would be naive but careful not to believe that we are the favourites," he said.