2005 Lions Tour: Second Test: Saturday, July 2New Zealand v Lions, Westpac Stadium, Wellington, 8.10am Irish time (live Sky Sports 1/RTE Radio 1)
* New Zealand lead the Test series 1-0 (First Test: NZ 21 Lions 3, Christchurch)
O'Callaghan is one of seven newcomers in Sir Clive Woodward's Test side, which also includes four positional changes from last weekend's Christchurch collapse.
Three Ireland players will start - O'Connell, one of three pack survivors from the first Test, O'Callaghan and flanker Simon Easterby - with Leinster hooker Shane Byrne and centre-cum-wing Shane Horgan both warming the bench.
There is a distinctly Welsh look about the Lions backline with newly installed skipper Gareth Thomas partnering the recalled Gavin Henson in midfield and Shane Williams - Tuesday's five-try hero against Manawatu - and Dwayne Peel also included.
Up front, Gethin Jenkins and Ryan Jones, in at number 8, tally up the Welsh player count to six. England boast six inclusions, with Jonny Wilkinson set back in his usual fly-half role for his first start at number 10 since the 2003 World Cup final.
The exciting Jones forms a new back row partnership with Leicester's Lewis Moody and Easterby.
Irish television presenter Hector S hEochagain hooked up with both O'Connell and O'Callaghan for interviews at Wednesday's press conference, much to the players' delight.
Meanwhile, New Zealand coach Graham Henry has made four alterations to his side for Saturday's second Test, with backline trio Mils Muliaiana, Rico Gear and Byron Kelleher and prop Greg Somerville, a late replacement for Carl Hayman (toe), all gaining starts.
Henry's un-enforced changes are surprising given the ease with which last Saturday's All Black XV seemed to hold the Lions at bay.
Full-back Leon MacDonald, winger Doug Howlett and scrum-half Justin Marshall are the players to miss out, with Howlett not even making this weekend's 22-man matchday squad.
"The players that are competing for those positions are of equal standing, I believe," Henry said at Tuesday's team announcement.
"Mils was probably the star player on last year's tour of Europe - he's a quality player. Rico was probably the form winger of the Super 12 from the New Zealand franchises. "The two halfbacks are of equal ability. We've had discussions with those two gentlemen prior to the Test series starting, saying that they would have an equal role, and that's what we've gone with."
Gear scored a Super 12 record-equalling 15 tries for the Crusaders this season.
Hayman, meanwhile, is out with an infected toe, which has failed to heal over a course of antibiotics.
Somerville comes in at tighthead prop while Canterbury front rower Campbell Johnstone comes in for bench duty.
"Carl's been on a course of antibiotics this week to deal with an infection in his foot," said Henry.
"He is responding to treatment, but it is a slow process. We were hopeful he would come right in time to play this weekend, but that is not the case.
"We are fortunate to have a player of Greg's quality who can step in."
New Zealand: Mils Muliaina; Rico Gear, Tana Umaga (Captain), Aaron Mauger, Sitiveni Sivivatu; Daniel Carter, Byron Kelleher; Tony Woodcock, Keven Mealamu, Greg Somerville, Chris Jack, Ali Williams, Jerry Collins, Richie McCaw, Rodney So'oialo.
BRITISH & IRISH LIONS:
(15) Josh Lewsey (London Wasps/England)(14) Jason Robinson (Sale Sharks/England)(13) Gareth Thomas (Toulouse/Wales) (Captain)(12) Gavin Henson (The Ospreys/Wales)(11) Shane Williams (The Ospreys/Wales)(10) Jonny Wilkinson (Newcastle/England)(9) Dwayne Peel (Llanelli Scarlets/Wales)(1) Gethin Jenkins (Cardiff Blues/Wales)(2) Steve Thompson (Northampton Saints/England)(3) Julian White (Leicester Tigers/England)(4) Paul O'Connell (Munster/Ireland)(5) Donncha O'Callaghan (Munster/Ireland)(6) Simon Easterby (Llanelli Scarlets/Ireland)(7) Lewis Moody (Leicester Tigers/England)(8) Ryan Jones (The Ospreys/Wales)
(16) Shane Byrne (Leinster/Ireland)(17) Graham Rowntree (Leicester Tigers/England)(18) Martin Corry (Leicester Tigers/England)(19) Martyn Williams (Cardiff Blues/Wales)(20) Matt Dawson (London Wasps/England)(21) Stephen Jones (Clermont Auvergne/Wales)(22) Shane Horgan (Leinster/Ireland)
Referee: Andrew Cole (Australia)