Sledging has abated but fierce rivalry remains
Before tonight's Ulster semi-final between the pair, let's look at the last time Donegal beat Tyrone in the championship.
The world of Gaelic football had a long, hard look at itself after that - and decided it didn't like what it had become.
That wet afternoon in May 2015 was shocking in the levels of physical exchanges alone, but sickening for the sheer amount of verbals between the sides.
The following week, 'sledging' was the hot topic. Sean Cavanagh was put up for interview at a corporate gig and said: "Well, there were a few verbals and I was involved in a bit of that."
Asked if some players were involved in researching family history in order to find offensive material on their opponents, Cavanagh added: "Yeah, at times, yeah. It can be very, very personal. I know there were certain players... who play for us who have been through tough times, and they were getting a fair bit of personal abuse... and it's not just all one side. It's both sides."
This was the endgame of two teams that had grown to despise each other.
The journey to that point had no real beginning just as it has no ending, but there was a fork in the road when Jim McGuinness became Donegal manager towards the end of 2010.
Former Tyrone player Joe McMahon explains: "The big difference in Donegal… as a Tyrone player, you didn't fear them. But 2011 was a turning point. McGuinness touches on that in the book he wrote, about the obsession they had with Tyrone. The obsession paid off.
"Tyrone were in control in 2011 and Donegal probably thought, 'Here we go again'. But they had a mindset, a belief and a quality at that stage. That day was a massive day for Donegal. They didn't fear Tyrone."
Donegal beat Tyrone 2-6 to 0-9 in the Ulster semi-final.
The next year, the giant game of chess in Clones represented the exact point where Donegal wrestled the power for themselves as they beat their old foes 0-12 to 0-9 in the Ulster final.
Donegal's hunger was passed back to Tyrone.
"Donegal were up there and were the team everyone looked to beat," says McMahon.
That pattern continued up to the 2016 Ulster final. Late points from Cavanagh, Peter Harte and Kieran McGeary finally breaking the curse.
"The elation in the changing-room and the celebrations afterwards, there was just this emotion," says McMahon.
Tonight, they are just too finely poised. The latest chapter will be written and nobody would be surprised at either outcome.
As McMahon said: "It's almost become like a club rivalry, it seems very parochial.
"I think the pressure is off Tyrone this weekend, but Donegal are sitting quietly and that's a danger for me."
The Ulster Championship at its very best.
- Tyrone v Donegal, live, RTÉ2/BBC2, 5.0