Monaghan will meet Tyrone in the decider after Mickey Harte's team defeated Fermanagh 2-9 to 0-7.
Fermanagh, managed by former Tyrone star Peter Canavan, kept in touch early on helped by three points from Daryl Keenan.
But Tyrone eventually broke the Erne men's resistance and goals from Plunkett Kane and Mark Donnelly helped them to a comfortable win.
In the first part of the double header, Down led up until the 67th minute but a Conor McManus point levelled matters with a point before Hughes sent over the winning scores.
McManus scored a goal in the first half which finished with the sides on level terms at 1-5 to 0-8.
McManus, who finished with a personal tally of 1-7, scored to put Monaghan ahead after the restart but Down responded to take the lead after points from Ryan Mallon point and Mark Poland.
Down edged ahead on three separate occasions in the second half but each time the Farney men hit back to level.
Both team finished with 14 men after Down's Keith Quinn and Monaghan's Karl O'Connell were sent off after receiving their second yellow card.