The crown of the champions is slipping fast after Dungannon surrendered this season's unbeaten home record to Shannon, the club who increasingly look like becoming their successors.
Defeat will have been especially disappointing for Stevenson Park coach Willie Anderson, who watched his side squander the majority of possession and territorial advantage to the streetwise visitors.
Anderson refuses to give up hope of making the top four and a play-off place, but now admits that the Tyrone club's away form must improve.
For Shannon, the roll continues. A sixth win from eight matches strengthened their position at the top of the table and increased hopes of reclaiming the crown which was their almost permanent possession in the 1990s.
The visitors didn't mind playing for long periods without the ball, such was their ability to strike at crucial spells of a game played under heavy snowfall.
With their back row helping to snuff out many of Dungannon's attacks at source, Shannon relied on potent full back John Lacey, who went over for two tries either side of the break.
Lacey's first - converted by Tom Cregan - was scored under the posts after he followed up on a cross-kick with the Dungannon defence stretched.
After scrumhalf Fiachra O'Loughlin had skipped his way around the Dungannon defence from the tail of a lineout for the game's opening try (also converted by Cregan), Lacey's effort opened up an 11-point lead and Dungannon could find no way back.
In between, winger Mark Bradley landed a penalty for Dungannon.
Shannon extended their lead to 16 points after the break when Lacey won the race to his neat chip in the 44th minute.
Dungannon raised the tempo and Bradley added two more penalties either side of an accurate effort from Cregan.
But it was not until deep into injury time that the home side were finally able to breach the Shannon line, full back Bryn Cunningham going over for a consolation try.
Scoring sequence: 15 mins: O'Loughlin try, Cregan conversion, 0-7; 19: Bradley penalty, 3-7; 31: Lacey try, Cregan conversion, 3-14; 44: Lacey try, 3-19; 51: Bradley penalty, 6-19; 61: Cregan penalty, 6-22; 68: Bradley penalty, 9-22; 82: B Cunningham try, 14-22.
DUNGANNON: B Cunningham; R Mercer, J Cunningham, A Redpath, M Bradley; I Humphreys, K Campbell; R Mackey, N Brady, G Leslie, K Walker, A Kearney, A Boyd, M Haslett, T Barker.
SHANNON: J Lacey; T Cregan, A Thompson, J Davis, M McNamara; N McNamara, F O'Loughlin; F Coche, J Buney, G McNamara, B Buckley, T Hayes, R Collins, G Noonan, D Quinlan
Referee: D Keane (Leinster)