When two tribes go to war: Donegal and Dublin really don't like each other much
The niggly undercurrent which sparked through the Dublin-Donegal league game last Saturday week will add to the tension when they meet in an even higher-stakes encounter in Croke Park on Sunday.
It promises to keep referee Maurice Deegan and his fellow officials busy on an afternoon which features football league semi-finals for the last time.
For while Dublin v Donegal is not one of the great traditional football rivalries, it has developed into one of the spikiest encounters, with a recent track record that suggests they don't like each other very much.
The latest instalment comes only 15 days after a game in which James McCarthy faced allegations of making contact with Martin McElhinney's eye and where Michael Murphy was sent off for a second successive year against Dublin. The former didn't stick after the GAA's disciplinary authorities decided the Dublin wing-back had no case to answer, while Donegal contended that Murphy was wronged - and not for the first time.
"I think Michael Murphy gets refereed differently to other players," said manager Rory Gallagher.
It was a return to a theme he raised after the Donegal-Tyrone Ulster championship last May when he said that "Michael comes in for a lot of attention off the ball which isn't allowed."
Murphy's dismissal last month was on a second yellow card, while he was black-carded against Dublin in last year's league. Dublin's Kevin McManamon also saw red in that game after being booked twice.
In 2013, Dublin's Kevin O'Brien had a three-match ban proposed by the Central Competitions Control Committee (CCCC) over an alleged biting incident in a League clash with Donegal, but was cleared by the Central Hearings Committee (CHC).
Two years earlier, Diarmuid Connolly was sent off in the second half of the low-scoring All-Ireland semi-final (Dublin 0-8 Donegal 0-6), which began the current phase of intense rivalry between the counties.
This Sunday's meeting will be the seventh in league and championship between them in that period with Dublin winning four to Donegal's one, while one was drawn.
Significantly, Donegal's only victory came in the biggest game of all - the 2014 All-Ireland semi-final, which they won by 3-14 to 0-17.
That remains an irritant for Dublin, who have since beaten Donegal twice in the league and who are now bidding to make it three in a row, thus remaining on track to win the title for a fourth successive year, a feat last achieved by Kerry in 1971-74.
Donegal ripped the Dublin defence apart in 2014 but struggled before and after, averaging 0-10 in five games against them.
That's largely due to the unyielding reliance on their famed defensive system which, at one stage in the recent clash with Dublin, led to 29 players jamming space inside the Donegal '45'.
It greatly restricts Donegal's attacking options but since they achieved so much off defensive stability from 2011-14 they are reluctant to refine it.
Jim Gavin spoke after the most recent Donegal game of his players "having fun" trying to break down massed defences, territory where Donegal are the market leaders.
However, it's not working against Dublin. Even in the 2014 All-Ireland semi-final, Dublin scored 0-17, which wins most games, only to be undermined by a defensive collapse under the weight of pressure generated by Donegal's breakouts.
It will be interesting to see if Donegal make any concession to a more open game next Sunday or whether they adhere rigidly to a system that's beginning to look jaded.
There's also the question of how committed they are to pursuing a league title on full throttle. They looked less than energised in last year's semi-final when conceding 4-11 to a Cork team in a four-point defeat.
However, there's a distinct difference between the two seasons. Donegal started the Ulster SFC on May 17 last year, whereas they are not due into action this season until June 12.
Dublin's commitment to the league has been relentless since Gavin took over at the start of the 2013 season, winning all three titles, and it shows no sign of abating.