Sexton will be partnered at half-back by Leicester's Frank Murphy, who started for Tigers in the recent Heineken Cup final and comes into this Irish side for Chris Keane.
In a rejigged back line, Sexton's place at full-back has gone to his Leinster colleague Ross McCarron, while Seamus Mallon's exclusion means Ireland Under-20 team-mates Darren Cave and Keith Earls will partner each other in a new-look centre combination.
Both Cave, who had Mallon inside him last week, and Earls, who patrolled the left wing last time out, scored tries on their 'A' debuts last week but against the Maori, the tournament's defending champions, they will be face their sternest examinations to date on the international stage. Earls' place on the wing has gone to Leicester's Johnny Murphy.
There is also one change to the pack that impressed against Canada, with Leinster's Stephen Keogh making way at number 6 for John O'Sullivan of Munster. Keane, Mallon and Keogh have all been included on the replacements bench, with Kieran Campell, Fergus McFadden and John Muldoon failing to make the matchday 22.
Ian Humphreys is unavailable for selection due to injury and his place in the squad has been taken by another of the Under-20 Grand Slam winners, Ian Keatley.
Ireland 'A' coach Michael Bradley has reiterated the point that there are a number of players in the 'A' squad in contention for a Rugby World Cup call-up. He said: "Eddie Oâ00Sullivan is in daily contact with us during the Churchill Cup. We're giving him updates on the players and how they progress.
"There are probably four or five of these lads who have a chance of making it to the World Cup â00 they're already on Eddie's radar and he has been clear on that for the last few weeks."
The 'A' team will again be captained by Connacht hooker John Fogarty, who was on the pitch in California last June when Ireland met the Maori in the 2006 Churchill Cup. Fogarty, Ray Hogan and Roger Wilson are the only players from the fifteen named for Tuesday's tie that started last year's match at the Buck Shaw Stadium.
The Maori ran out convincing 27-6 winners back then, with Paddy Wallace (penalty) and Rob Kearney (drop goal) scoring the points for Ireland 'A'.
A win for Ireland 'A' over the Maori at Exeter's Sandy Park would see them qualify for the Churchill Cup final, which takes place at Twickenham on Saturday. Defeat would send them into the Plate final, which they won last year - beating England Saxons 30-27 in Edmonton, Canada.
The Ireland-Maori match will be broadcast live on Sky Sports 1.
IRELAND 'A' TEAM AND REPLACEMENTS (v New Zealand Maori, Churchill Cup, Tuesday, May 29, Sandy Park, Exeter, 8pm):
15 - Ross McCarron (UCD/Leinster)
14 - Paul McKenzie (Belfast Harlequins/Ulster)
13 - Darren Cave (Belfast Harlequins/Ulster)
12 - Keith Earls (Thomond/Munster)
11 - Johnny Murphy (Leicester Tigers)
10 - Johnny Sexton (St. Mary's College/Leinster)
9 - Frank Murphy (Leicester Tigers)
1 - Ray Hogan (Galwegians/Connacht)
2 - John Fogarty (Buccaneers/Connacht) (capt)
3 - Michael Ross (NEC Harlequins)
4 - Ryan Caldwell (Dungannon/Ulster)
5 - Andrew Farley (Buccaneers/Connacht)
6 - John O'Sullivan (Garryowen/Munster)
7 - *Johnny O'Connor (London Wasps)
8 - *Roger Wilson (Belfast Harlequins/Ulster)
16 - Sean Cronin (Shannon/Munster)
17 - Declan Fitzpatrick (Belfast Harlequins/Ulster)
18 - David Gannon (Buccaneers/Connacht)
19 - Stephen Keogh (Shannon/Leinster)
20 - Chris Keane (Buccaneers/Connacht)
21 - Seamus Mallon (Northampton)
22 - John Hearty (Galwegians/Connacht)
N.B. *Capped at full international level
Tour Management -
Michael Bradley (Coach)
Allen Clarke (Assistant Coach)
Joey Miles (Manager)
George Murray (Video Analyst)
Simon Harland (Physiotherapist)
Des Ryan (Fitness Advisor)