The fly-half debate has been one of the most-talked about areas in Irish rugby over the past couple of seasons and it was Sexton who appeared to have cemented his position as first choice.
But triple Lions tourist O'Gara has never been far behind and his form in this World Cup to date has surpassed that of his Leinster rival.
O'Gara started last week's handsome win over Russia, while he and Murray made impressive contributions in the latter stages of the famous victory over Australia.
"Ronan and Conor went well in the last 20 minutes against Australia. Ronan went well against Russia as well," said Kidney, who insisted he hadn't turned to O'Gara just because of his superior goal kicking.
"This is the right combination for us against Italy. They've played a few times together now.
"Ronan has been place kicking well, but if Jonathan Sexton was starting on Sunday it wouldn't worry me.
"I'd hate to go down the road that we're picking Ronan because of his place kicking. He's too good a player to be saying that about him while Jonny's place kicking is not of concern to me."
Murrayis set to start just his second Test as Ireland search for the win that would secure top spot in Pool C.
Lions stars Tommy Bowe, Brian O'Driscoll, Gordon D'Arcy and 2009 tour captain Paul O'Connell are fit to start, as are fellow Lions Rob Kearney and Keith Earls and in-form flanker Sean O'Brien who all missed training this week but have since recovered from minor knocks.
Ireland include a total of 10 Lions in their starting line up, with six of those coming in a start studded backline.
But while victory would see Kidney's men march on to the last eight, defeat is likely to lead to a premature exit for the second World Cup in succession.
Ireland (vs Italy, Dunedin, Sunday, 8.30am BST)
Rob Kearney; Tommy Bowe, Brian O'Driscoll (capt), Gordon D'Arcy, Keith Earls, Ronan O'Gara, Conor Murray; Cian Healy, Rory Best, Mike Ross, Donncha O'Callaghan, Paul O'Connell, Stephen Ferris, Sean O'Brien, Jamie Heaslip
Replacements: Sean Cronin, Tom Court, Donnacha Ryan, Denis Leamy, Eoin Reddan, Jonathan Sexton, Andrew Trimble
NB Bold denotes Lion