On Sunday, the 17-year-old football sensation is likely to play some role in the county's All-Ireland SFC qualifier against All-Ireland champions Tyrone at Croke Park.
But 24 hours earlier he is due to line out in the All-Ireland MFC quarter-final against Cork at the Gaelic Grounds in Limerick. Laois boss Sean Dempsey has selected Brennan at full forward on an unchanged side from that which won the Leinster final.
"We came through the toughest side of the draw in Leinster defeating Meath, Dublin and Kildare in the final but we won't be taking any chances with Cork," said coach Dempsey.
"Cork are in a similar position to us last year when we lost the Leinster final and came back through the qualifiers to win the All-Ireland.
"We played them in a challenge game earlier in the year and they beat us. I was very impressed with their play and was surprised they failed to win the Munster title.
"I'm a great admirer of Cork. When they turn on the style they are more than a match for the best. Obviously they are hurting from their Munster final defeat and we'll have to be at our very best to beat them."
Colin Begley, Brendan Quigley, Craig Rogers and Brennan all toured Australia with the Irish U17 team earlier this year.
Not unexpectedly the Cork selectors have made a number of changes.
Kevin O'Halloran takes over at full back with Niall Horgan moving to centre back and Eoin Cadogan taking Stephen Keohane's place at left half back.
Paul Kerrigan Kevin Canty are recalled to the team at left-half and left full-forward respectively. Positional switches sees Carthrach Keane back out at midfield, and Fintan Gould and Colm Callanan at right corner and full-forward respectively.
Tyrone have made one change for their quarter-final clash with Roscommon at Breffni Park. John Gilmore comes in at right half-back to replace Brendan Boggs, ruled out by injury.
PJ Quinn, an impressive substitute in the Ulster final replay win over Down, looked set to come into the Ulster champions' rearguard, but he too has been sidelined by an injury.
Skipper Marc Cunningham has recovered from flu and plays at centre-forward. Stephen Donaghy moves from left half-forward to the corner in a direct swap with Ronan McCrory.
E. Culliton; C. Healy, M. Timmons, B. Meredith; K. Smith, C. Begley, N. Donoghue; B. Quigley, C., Rogers; E. Butler, I. Fleming, S. O'Leary; M. Tierney, D. Brennan, D. Conway.
Ken O'Halloran (Bishopstown); S. O'Donoghue (Ballincollig), Kevin O'Halloran (Mallow), K. Harrington (Bantry); M. Shields (St. Finbarrs), N. Horgan (St. Nicks), E. Cadogan (Douglas); A. O'Sullivan (Castletownbere), C. Keane (Newcestown); D. Crowley (Bishopstown), D. Goulding (Eire Óg), P. Kerrigan (Nemo Rangers); F. Gould (Macroom), C. Callanan (Clonakilty), K. Canty (Valley Rovers).
: T. O'Connor (Douglas), G. O'Shea (Nemo Rangers), J. Lane (Douglas), D. Harrington (Garnish), A. Fenton (St. Vincents), F. Lynch (Valley Rovers), A. Concannon (Ballingeary), J. Halbert (Glenville), D. McCarthy (Kilmurry).
D McCann; N McGinn, P Marlow, D Burke; J Gilmore, N Kerr, M Murray; R Mulgrew, S O'Hagan; C O'Neill, M Cunningham, R McCrory; G Devlin, C Cavanagh, S Donaghy.