Eathorne scored a magnificent unbeaten 158 to help North Otago achieve a first-innings win over Mid Canterbury earlier this month.
Eathorne and Scott Simpson are both unavailable due to club cricket commitments in Dunedin.
Former Otago physiotherapist Duncan Drew will replace Eathorne in the starting XI.
"Sean carried the batting for us, but Duncan is in quite good nick with 140 in club cricket a couple of weeks ago. So we are hoping he will carry that form through," North Otago Cricket Association chairman Peter Cameron said.
Former New Zealand left-arm bowler David Sewell will spearhead the attack.
Otago Country has lost seven players from the side which played in the South Island play-off against Canterbury Country last season.
Otago opening batsman Leighton Morgan is arguably the biggest loss.
He scored 299 runs at a Bradman-like average of 99.3 last season.
But the departure of off-spinner Will Somerville will also dent Otago Country's prospects.
Somerville took 11 wickets at 25.9.
However, team manager and convener of selectors Malcolm Jones is confident the return of players like Ronnie Kotkamp will ensure the team is competitive.
"We still have a very experienced team at Hawke Cup level, with only two players [Ollie Newton and Barry White] making their debut," Jones said.
Talented all-rounder Brendan Domigan is expected to be one of the leading players.
The Otago Country skipper has been on the fringe of the Otago side and was unlucky not to play for the major association, Jones said.
"Brendan has played Hawke Cup cricket for us since he was 15 and at 25 or 26 he has had a huge amount of experience. Last year he was the batsman and player of the year for Otago Country."
Kotkamp is a survivor from the team which won the Hawke Cup in 1996 and will take the new ball with promising medium-fast bowler Ben Purvis.
Purvis' father, Neil, who died last year, played 12 games for the All Blacks, including one test, and played Brabin Cup cricket for Otago.
Otago Country v North Otago
Alexandra, today and tomorrow
Otago Country: Brendan Domigan (captain), James Pyle, Cam Fawkner, Fraser Wilson, Brayden Hill, Scott Paulin, Ollie Newton, Barry White, Jason Domigan, Ronnie Kotkamp, Ben Purvis.
North Otago: Darren Broom, Ben Cant, Peter Cartright, Sean Conlan, Duncan Drew, James Ferris, Jordan Horrell, Paul Odell, Glen Paterson, David Sewell, Dave Simpson, Chris Smith.
