Before the ball is even thrown in this afternoon, we will find out who Jim McGuinness considers to be Galway's biggest scoring threat - Damien Comer or Shane Walsh.
So far this year, Donegal full-back Brendan McCole has been his team's dedicated man-marker - conceding just nine points from play or marks in seven matches.
In those encounters he has faced Darragh Canavan twice, holding him scoreless from play in their most recent meeting and without a touch in extra-time in the Ulster semi-final. He held Shane McGuigan scoreless for 70 minutes until he kicked over two points in injury time as McCole dropped back to deny any late goal chance.
He has also marked a roving Sam Mulroy, Andrew Murnin and then Conor Turbitt against Armagh, conceding just 0-01 on each of the Orchard forwards and 0-02 off the Louth marksman. Brian Hurley was also kept scoreless while on him during the first half against Cork, and Clare's Aaron Griffin, who slotted 1-08 in his other four championship games, didn't get a shot away before being replaced in their match-up.
McGuinness' Donegal team go forward and defend as a unit, with a backline made up of an attack-minded half-backs, and converted midfielders or half-forwards. Together the six named starters have scored 2-33 from play in five games with Donegal defenders as a collective accounting for over a third of their team's total from play and an impressive average of 0-06 per game.
At the other end, they swarm numbers around the danger zones with McCole -who is the lowest scoring of the six starting backs with just one point thus far - set to again be the only out-and-out defender to begin the game for the Ulster champions.
However against Galway the decision of who to assign him to could prove the decisive factor in their All-Ireland semi-final at Croke Park.
Both Comer and Walsh carry a lethal scoring threat. Both have been managing injuries during the 2024 championship, with Comer scoring 0-05 in five games, starting just three of them.
Walsh has 1-11 in seven games, starting six of them. Featuring in 16 games over the past three championship seasons, Comer has scored 3-23 from play, and in 19 games Walsh has scored 2-27 excluding placed balls.
While Walsh receives closer man-marking attention and often drifts further from goal more often, Comer is statistically just about the bigger scoring threat but ultimately it's so close it'll come down to McGuinness' judgment call.
Brendan McCole
McCole is the closest physical match-up for Comer who is an intimidating, abrasive ball-winner, however against Tyrone he was on Canavan with the rangy Conor Moore picking up a similar profile in Cathal McShane.
Against Armagh he started on the towering Murnin but after Turbitt had kicked three points from play within 25 minutes on Moore the two switched. He was also put on Mulroy who drifts much deeper out the field than his other assignments, similar to Walsh. With limited options McCole has simply been put on the opposition's biggest scoring threat in the inside line regardless of their playing style or physical make-up, which has made his performances all the more impressive.
Galway will be by a distance the strongest full-forward line Donegal will have faced however, and while McCole has shown he is adaptable he does have his strengths and perceived preferences.
Against Mulroy he opted to stay in a defensive position once the Louth forward drifted into his own half. Mulroy joined the attack from such an area for his first score from play, ultimately cutting in from the right wing with McCole picking up in the full-back line. Murnin also created opportunities from deep with McCole not comfortable tracking. Man-marking defensively and tracking all over the field are two different skillsets and if McCole picks up Walsh he will have to stick to him wherever he goes.
Comer then is a more natural fit for the Donegal number three, albeit one recent habit of his may be exposed by the Galway full-forward. Murnin only managed four touches whilst being marked by McCole for almost 30 minutes, however he did score an excellent point in that time. Receiving a handpass into him, he took the ball on the turn and pointed first time.
The St Naul's defender is an intelligent marker, a strong tackler, a composed presence and a rare physical hybrid both able to contest 50:50s with the biggest of them and move his feet quickly enough to pen-in the most diminutive of forwards.
His discipline in sticking to his man and getting the distance right to discourage an easy pass and at the same time protect against a cut inside restricted McGuigan to just 14 touches, Canavan to 13 on two occasions, Griffin to five, and Turbitt to five in the second half with his point coming whilst McCole had dropped back on Murnin in the square.
McCole then is the insurance policy and the outlier in McGuiness' all out attack/defence system
The flaw exposed by Murnin however is a habit of being teased in and committing whenever there's a chance of getting a hand in on the initial pass to a forward. This leaves him vulnerable to be turned and lost, particularly against Comer who looks to do this on repeat.
Canavan, and Mulroy against Louth, both scored in a similar fashion. Whereas against Griffin for Clare he got a hand in on five occasions, and the one ball that was kicked into McGuigan against Derry he got something to first. So deciding when to commit or not will be crucial in that prospective match-up.
Second time around against Canavan, McCole struck the balance perfectly between bringing his forward up the field and not being caught out upon a counter. Of his nine points conceded four were when out of position upon a turnover or with him covering elsewhere. Against Tyrone in Ballybofey he had five involvements in the opposition 45, the same amount as in his other six games combined and Canavan was kept scoreless.
McCole has scored one point off one shot, in a last ditch attempt to rescue extra-time in the Ulster semi-final. All around him Eoghan Ban Gallagher has scored 1-01 since returning to the team, the versatile Ciaran Moore has six points, Peadar Mogan has 0-13 and Ryan McHugh 1-10, with Caolan McGonagle often the line breaker but also adding 0-02 himself. McCole then is the insurance policy and the outlier in McGuiness' all out attack/defence system. However against Armagh, after Turbitt's substitution, and for much of the second half against Cork, he joined that overall system rather than man-marking.
McCole tackling Louth's Sam Mulroy during the All-Ireland quarter-final
This is a system which - if Galway's star players win their fitness battles - is about to face its toughest battle. A gameplan which sees defenders put forwards on the back foot, suffocate them through sheer numbers and then run the legs off them. If Comer is to be picked by McCole, Mogan could well mark Walsh as he did against Tyrone's Darren McCurry or Rory Grugan of Armagh. Against the former he conceded three points from play/marks but was man of the match with 0-03 of his own and McCurry was taken off. He has the speed and footwork to defend capably but his approach will centre on keeping his forward in their own half or with hands on knees.
With McCole flying the flag for out and out defenders, the success of his colleagues in the Donegal defence will be doing the opposite.
Ultimately the match-ups will come down to - who does McGuinness believe his system can nullify best, and who needs the attention of his lone man marker. Comer or Walsh?
Watch the All-Ireland Football Championship semi-final, Donegal v Galway live on RTÉ2 and RTÉ Player from 3.15pm. Follow a live blog on rte.ie/sport and the RTÉ News app and listen to commentary on RTÉ Radio 1
