JOE McQuillan could emerge as the key figure in dictating the shape of next Sunday's Donegal-Tyrone Ulster quarter-final showdown in Ballybofey.
While much of the pre-match fascination centres on the likely tactical manoeuvres deployed by Jim McGuinness and Mickey Harte, the impact of the Cavan referee will be equally important, according to former All-Ireland winning manager with Down, Pete McGrath.
"We're going to get some very big collisions and physicality taken to high levels so how Joe responds to that will be crucial. I hope he restrains himself and doesn't step in too often because that would ruin the game as a spectacle. I'm not talking about letting foul or dirty play go unpunished but if the hits are fair and properly delivered, it shouldn't matter how hard or often they are.
"It might not always be easy to distinguish between what's legal and what's not but Joe is an experienced referee so I'm sure he will get most of the calls right. I just hope he doesn't become too fussy. These are two very powerful sides but they are also very good footballers so let's see what unfolds when they go at each other at full force," said McGrath.
He believes that Tyrone's obsession with not losing to Donegal for a third successive year will be a major driving force for both Harte and a squad which made considerable progress throughout the league, eventually finishing as runners-up to Dublin.
"Tyrone squeezed every last ounce of value – other than winning the title – out of the league in terms of working new players into the squad, developing a system of play and gaining valuable experience so they are ideally placed for this challenge," he said.
"As for the pattern of play, I would expect it to be based on both sides trying to apply a vice-like grip to the opposition's main danger men. There will be a lot of congestion down the middle and very little space on the wings. Both sides will use their strong runners to try and break the first tackle because otherwise it's going to be very difficult to make progress."
While Tyrone are an impressive work-in-progress, Donegal are heading into new territory as they attempt to defend their Ulster and All-Ireland crowns. Winning the Ulster treble would be a huge bonus for them, prior to regrouping for the All-Ireland bid and while McGuinness is known for his attention to detail, McGrath believes there is one area for which no amount of planning can prepare a team.
"When you win an All-Ireland final, you're in a different zone. You have worked so hard to get to the summit and now you're being asked to do it again. Everything can appear to be spot on in training but you can never be sure if it is until the real pressure comes in a game. Jim is well qualified to look for signs but even he won't be sure of the squad's exact mindset until the full heat comes on," said McGrath.
Despite the uncertainty as to whether Donegal can carry the intensity of the last two seasons into a third campaign and Tyrone's determination not lose to them for a third successive year, he believes the All-Ireland champions will remain on the direct route to retaining the title.
"Tyrone are on their way back as a major force – there's no doubt about that – but this particular test may have come a year too early. Donegal have enough experience and physicality to win, provided the mindset is right.
"However, they will need Karl Lacey to be fully fit and, again, there's no way of knowing that for sure until the real pressure comes on," McGrath added.
"If he is, and Donegal are driven by the same desire as over the last two years, I'd expect them to win a low-scoring game. Of course, that certainly wouldn't be the end of Tyrone's All-Ireland chances. Mickey has a great record when it comes to regrouping through the qualifiers so even if Tyrone lose on Sunday, they still have a lot to look forward to this year."
A former All-Ireland senior winning manager with Down in 1991 and 1994, McGrath is in charge of the county's minors this year.