The Lions are still licking their wounds from the 19-13 loss to the Maori in Hamilton last Saturday.
But Munster lock O'Connell, a favourite to pin down one of the Test team second-row positions against New Zealand in 11 days' time, believes the setback could have a positive effect.
"I think when you look at it, the reaction to the loss has been great," the 25-year-old said.
"We stood there in the dressing-room afterwards and had a bit of a chat between all 45 players in the squad.
"That could end up being a landmark game for us on the tour. It was as tough a game as you can get, and it was right up there with Test-standard rugby."
Ireland flanker Simon Easterby makes his tour bow after flying to New Zealand as replacement for a stricken Lawrence Dallaglio.
And there are more back-row injury problems for the Lions, with Leicester flanker Lewis Moody remaining at the squad's Christchurch base to await further scrutiny on a left knee injury.
Moody's place among the substitutes against Wellington has been taken by England colleague Richard Hill, and Lions coach Gareth Jenkins revealed Moody is already "out of the selection process" for Saturday's appointment with Otago in Dunedin.