O’Driscoll, who overtook Willie John McBride to become the longest serving Lion of all time in Melbourne, was cut from the matchday squad for Saturday’s decisive Test against the Australians.
Last night 1983 tourist Campbell was still trying to come to grips with Gatland’s call.
He blasted: “It is arguably the biggest and most controversial decision in the long history of the Lions. Win, lose or draw, it will register very high on the Lions Richter scale. I heard it at seven in the morning and hours later I’m still in shock, I really just can’t believe it.
“It’s a decision many people simply won’t be able to understand, not least in the light of the fact you don’t have your tour captain Sam Warburton, you don’t have Paul O’Connell, so you’re looking at what should have been an automatic selection for captain.
“The thought he wouldn’t be in the team didn’t even cross my mind. I had figured he would be captain and that he would finish his Lions career by leading the squad to a long-awaited series win.
“Obviously Warren Gatland has made a very hard-nosed, very pragmatic decision. He will live or die on this one decision, the biggest decision of his coaching career.
“If the Lions win the match and the series, I think he will be seen as something of a genius in Wales. But I don’t think he will ever be seen as a genius in Ireland.”
Campbell said he was certain O’Driscoll would again have hooked up with Jamie Roberts to create an intense headaches for Australia’s midfield defence: “Roberts was a massive loss, the fact he is back made it logical to me to link up with Brian again. It’s a very strange decision and I don’t understand it. This isn’t about sentiment for Brian. Either it will go down as courageous or foolhardy in the extreme.”