The winner of Sunday’s opener faces Fermanagh 13 days later with a semi-final against either Donegal or Down to look forward to.
McMahon is “leaning towards Armagh and Donegal” to meet on 3 May but what of the other side of the draw?
Derry host Antrim on 18 April with Cavan at home to Monaghan the following day – both games live on the BBC – with the winners meeting in a 2 May semi-final.
While the Oak Leafers missed out on promotion from Division Two, they found form after a difficult 18 months and “are definitely back on the road” according to the former Dublin defender.
Should they overcome the Saffrons, then who do they face from the following day’s derby?
Monaghan lost their Division One status after a difficult campaign, while Cavan managed to survive in Division Two.
Neither are on a hot streak, but McManus notes “there’s an opening for any team on that side of the draw to get to an Ulster final, so it’s a big game”.
“Division One is a very unforgiving place to be when you have a lot of injuries and you are blooding a lot of young lads at one time,” McManus said of the Farney men.
“We saw that the first day against Armagh and it just followed that pattern the whole way through. They had a good performance against Donegal and hopefully they will have four or five lads back like Ryan McAnespie, Conor McCarthy, Killian Lavelle, Dylan Byrne, Louis Kelly.
“Cavan aren’t firing on all cylinders either but on their worst day, Cavan or Monaghan can always get themselves up for that game.
“Neither team are coming in on the crest of a wave, so if ever there was a 50-50 game, this is it.”