Much has been made of Warburton's age with the 24-year-old becoming the youngest player to lead the tourists for 58 years, but O'Connell was struck by his maturity when the two roomed together during last week's training camp in Wales.
"I haven't spoken to Sam directly about the captaincy. Last week we chatted non-stop about all manner of things," the 33-year-old said. "It's important that he knows myself, Brian O'Driscoll and all of the senior players are there for him. But having spent a week with him it seems to me he'll be perfectly fine. He's a very relaxed guy and confident in his own ability."
The Ireland man added: "He's been very successful with Wales and it's important we back him as much as we can, but I don't think he'll need a whole lot of it. I was 25 on the 2005 Lions tour to New Zealand and was probably a lot more naive than Sam. He's quite a wise guy, wise beyond his years."
While O'Connell's epic performance against Harlequins in the quarter-finals of the Heineken Cup last month catapulted him into contention for the captaincy, the Munster second row is merely happy to be involved in any capacity.
Injury has prevented him from adding to his 85 Ireland caps for the past year with back surgery heavily disrupting the current season, but his recent form made him impossible to omit.
"Right up until selection I didn't know if I'd be picked having not played any international rugby since last March and very little rugby since the previous May," he said. "It was hard to know if they'd even consider me. I hadn't spoken to (head coach) Warren Gatland or anyone during that time.
"People asked me would I have been disappointed if I hadn't been selected, but I wouldn't because I got back from a fairly serious injury as quickly as I could and played as well as I could. So when you give everything you have and come up short, that's just the way it is. There's no point in complaining about it.
"There was so much speculation about this tour. In the Six Nations someone would play a good game one week and they'd have pencilled themselves in for the tour, they'd play badly the following week and have written themselves off, then they'd play well the next week and pencilled themselves in for captaincy.
"So I tried to avoid the speculation as much as I could, it's something that probably does you no good following it too closely."
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