THIS PAIRING is so well balanced in historical terms that just one win in over a century separates Galway from their neighbours and in recent years the verdict has swung unpredictably between the teams.
Last year is of significance. Going into the Connacht first round in Pearse Stadium, a broad and in many ways unthinking consensus elevated Mayo to favouritism, largely on the basis of John O'Mahony's return to the county.
Nine years after O'Mahony had guided Galway on the preliminary steps to an historic first All-Ireland in 32 years in Mayo's back yard he found himself in a similar position with roles reversed.
In May of last year Mayo were, as in 1998, recovering from defeat by Kerry in the previous year's All-Ireland final and ended up being knocked out of the Connacht championship by their near neighbours - except on this occasion O'Mahony was back in charge after 16 years performing great feats elsewhere in the province.
The scale of the defeat was savage. Seven points was just a conservative version of Galway's superiority and it was a wounding experience for the Mayo manager, the impact of which was sharpened in public perception by the imminent general election, in which O'Mahony stood - successfully despite his trials in Salthill - just a few days after the match.
O'Mahony doesn't forget such setbacks and it's not hard to believe he has had this fixture targeted since the conclusion of that glum return season with his own county.
But on what basis have Mayo edged ahead of Galway? Why should this be different from what happened last year?
The teams are hugely changed. Mayo have eight different players starting, whereas Galway have six, albeit a couple of changes are injury-enforced.
There were a couple of areas of primary damage last year. Mayo's defence was given an impressionist touch by the decision to switch players all over the place. This was rendered all the more puzzling by the outcome whereby Galway's forwards, who simply followed their markers, adapted far more comfortably to the change.
There was also a weariness, a lack of urgency, about Mayo that contrasted ruinously with Galway's zippier approach. We can expect that to change tomorrow.
Joe Bergin's injury has created big problems for Galway's centrefield and although Ronan McGarrity hasn't always convinced at the very top level he has traditionally been well able for these matches and missed last year.
Tom Parsons beside him is one of the talented younger players coming through, and unless Galway have a particularly cunning plan Mayo will win this sector.
Although Galway can win without gaining a decisive edge at centrefield they won't win if they are conspicuously second-best.
Mayo do, however, need a clear superiority here because their attack is not high-yield.
The home forwards will, however, convert good possession and Galway look weaker at the back than last year because Damien Burke's form is not as good and even though Diarmuid Blake is a welcome return, he lacks match fitness, and Finian Hanley was stretched against Leitrim.
MAYO:D Clarke; K Higgins, K Conroy, C Boyle; T Cunniffe, D Heaney, J Nallen; R McGarrity, T Parsons; A Dillon, P Harte, T Mortimer; C Mortimer, A O'Malley, A Moran.
GALWAY:P Doherty; G Bradshaw, F Hanley, D Burke; N Coyne, D Blake, G Sice; B Cullinane, N Coleman; C Bane, P Joyce, N Joyce; M Clancy, M Meehan, F Breathnach.
Referee:D Coldrick (Meath).
Guidelines Mayo v Galway
In the last episode:The counties have met on an almost annual basis this decade. In the past five championships the winners have alternated, with a couple of NFL semi-final collisions thrown in. Last year Mayo were well beaten in Salthill.
You bet:This as finely balanced in the bookies as elsewhere. The home side are marginally preferred at 10-11, with Galway at 6-5. The handicap is slender. Mayo (-1) are 5-4 whereas Galway (+1) are 4-5.
On your marks:The enduring menace of Pádraic Joyce remains a significant weapon for Galway, even if the county's most distinguished forward of the current era is well into his veteran phase. Unusually he wasn't at his most productive a year ago when the team nonetheless won easily. David Heaney did the marking then and gets the detail again this weekend. If he repeats the shutout of 14 months ago Mayo will win.
Gaining ground:This will be the last meeting of the rivals at McHale Park in Castlebar. The famous venue is due to close for extensive renovation.
Just the ticket:Stand tickets are €35, sideline tickets €25 and terrace €20.
Crystal gazing:Galway were the more likely winners for most of the NFL but have picked up injuries and had flaws exposed in the meantime, whereas Mayo's championship has shown signs of smoother acceleration and take-off looks more imminent.
