lionsrugby.com and James Mortimer 21.May.2013Getty Images
"We roomed together last week and chatted non-stop about all manner of things," said O'Connell.
"Having spent a week with him he will be perfectly fine. He's a relaxed guy, very confident with his own ability and has been very successful with Wales."
Warburton, at 24-years-old is the Lions youngest captain in more than 50 years but O'Connell has vowed to do all he can to support the Welshman
"I don't think I could do that job at 24, I was 25 in New Zealand and was a lot more naive than Sam," said O'Connell.
"He's a wise guy, wise beyond his years and he seems to be very much in control and confident in his own ability.
"But it's important that he knows that myself, Brian and whoever else from the senior group of players are there for him.
"It's important that we back him up as much as we can."
For O'Connell however, just earning selection for a third Lions tour was a bonus. The colossal second-row had been plagued by injuries over the last year and missed the entire RBS 6 Nations.
But he can hardly believe how time has flown since 2009 and is relishing every minute of his latest Lions experience.
"It's incredible how quick it has gone," said O'Connell.
"It's nice when you come in here and there's a few familiar faces like Mike Phillips, Adam Jones and Alun Wyn Jones. It seems like you're almost on the same tour.
"In 2009 it seemed a mile away but it's incredible to be here now with only six days to go.
"Six months or even three months ago I didn't think I would be here so it is all a bonus. I'm a lot more relaxed than four years ago.
"Right up to selection I didn't know if I would be involved or not. It's hard to know having not played any international rugby since last March and very little rugby since the previous May.
"I hadn't spoken to Warren or any of the staff. I wasn't sure until my name was read out. The fact Munster did great and I was Involved in a few big games game probably helped but I wasn't sure at any stage that they were considering me."