The sides' fortunes have flipped in the three years since their last semi-final to leave Mayo as favourites but tomorrow's All-Ireland football semi-final comes with more complications than a simple reversal of fate.

Kerry arrive with a much-changed team and bathed in an aura that suggests the graph of the counties' progress may be about to cross once more. Since losing Colm Cooper to injury earlier in the year, Eamonn Fitzmaurice's team have had a perfect alibi for not thriving this year but so far have not needed it.

Tomorrow is however their sternest challenge and if the same is true of Mayo, the Connacht champions are on track for third successive final and only at that exalted level have they faltered since last playing Kerry in the championship.

The charge of not having been sufficiently tested carries more weight when levelled against an emerging team like Kerry and indeed, Mayo’s problems also centre on having been too tested in some of their matches.

Significant losses

There are intrigues in both selections. Part of the reason Kerry are so new-look is that Fitzmaurice hasn’t started Declan O’Sullivan or

Bryan Sheehan

because they ran out of road recovering from injury and will instead start on the bench.

Both are significant losses in that O’Sullivan at his best conducts the team and Sheehan’s dead ball kicking is a major asset in matches like this. Assuming both get to play at some stage they are weighty additions to a replacement list that boasts four former All Stars, including a Footballer of the Year.

Mayo have named an unchanged side from the team that got past Cork although no-one expects that to be the starting 15. Jason Gibbons, whose good form in the early part of the year seemed to assure him of a championship jersey until injury intervened, is likely to come in at centrefield with Donal Vaughan reverting to defence.

There has also been speculation that team captain Andy Moran will start on the bench with the intention that he reprise his impact sub's role against Roscommon and that Alan Freeman will come in.

At his best, Freeman is an excellent option at full forward and was Man of the Match in last year’s semi-final but he hasn’t been starting regularly this season, which can be an inhibition for a confidence player, whereas Moran’s recent Croke Park form hasn’t been bad and he was beginning to motor when replaced against Cork.

Mayo's strength in the middle third has been identified as the cockpit of tomorrow's semi-final and there are significant issues here. They will include to what extent Anthony Maher can rediscover form at centrefield for Kerry against an ultra-competent Mayo unit and if his partner David Moran can iron out the occasional tendency to carelessness and whether Peter Crowley can rein in Aidan O'Shea on the 40 and the half backs in general close down the middle through which Galway prospered.

Both full back lines had frailties the last day but Mayo will be stronger if Tom Cunniffe drops back – they'll need to be with James O'Donoghue in such free-wheeling form and Paul Geaney offering substantial support.

Tighten up

Mayo for all the frustration and suggestions of stagnation have a wealth of experience and under Horan, a reputation for reliability.

They need to tighten up on the defensive lapses that let Cork back into the match but they’re unlikely to let attention wander this time. Up front they’ve been impressive and their full-court presses in the quarter-final produced shooting statistics more usually associated with Dublin. In what is expected to be Horan’s last year, the graph of the counties’ progress may be about to cross – but not yet.