Four years ago the Lions opened their tour of Australia with comfortable victories over Western Australia and a Queensland President's XV which did little to test their Test-match credentials.
The Lions racked up 199 points in those two games but ended up losing the Test series to the Wallabies.
That they had a soft opening is not by any means the only reason Graham Henry's side failed in Australia, but O'Sullivan is convinced a tough start against Bay of Plenty, Taranaki and a Test-standard New Zealand Maori XV will be the ideal preparation for beating the All Blacks.
"Every game we play here in New Zealand we will be tested," O'Sullivan said.
"That makes a Lions tour unique and if we don't go into every game with that mentality we will get turned over. That starts a week today in Rotorua where Bay of Plenty will try and throw the kitchen sink at us.
"We have got to get our heads around that very quickly. That will make us a better team.
"We will get to the Test side knowing all the players have been put through the mill and we know what we are picking from.
"It gives you the best opportunity to pick your strongest side to win the series. That is why we are playing all these tough games."