Number 8 Michael Graham was the hero for Ballynahinch at College Park as his injury-time try helped Ballynahinch to a dramatic 28-21 victory over Dublin University.
The result consolidates 'Hinch's position at the top of Division 1B table - they now have a nine-point lead over both UCD and Dublin University.
Although they will need one more win at least to be sure of finishing in top spot, it seems almost certain that the County Down club will playing in the top flight of the Ulster Bank League next season.
Having gained promotion from Division 2A last season in spectacular fashion, Trinity have been pushing hard for promotion throughout the current campaign.
The students were quick out of the blocks in this encounter, as out-half David Joyce gave them the lead courtesy of a close-in penalty with just three minutes gone.
'Hinch were finding it difficult to settle into their usual groove and the hosts took full advantage as a second successful place-kick from Joyce moved them into a 6-0 lead by the 17th minute.
At this point, Tony Smeeth's charges were playing with real confidence, but they allowed their opponents back into the reckoning when a mistake by Neil Hanratty allowed the pacy Aaron Ferris to break through unopposed for his side's first try of the game.
Right winger Michael Lawton expertly slotted the conversion and even though Trinity once again piled on the pressure in the scrum, the table toppers were able to ride out this particular storm.
With just two minutes remaining in the first half, 'Hinch registered their second try. Powerful work from a maul led to a penalty try being awarded by referee Eddie Hogan O'Connell, and Lawton added the simple conversion.
The hosts were never going to allow their heads to drop however, and a third penalty from Joyce just before the break reduced the deficit to five points (14-9).
Indeed, just five minutes into the second period, they managed to completely wipe out their Ulster rivals' lead when flanker Pierce Dargan reached over in the left corner via a telling lay-off by the increasingly influential Joyce.
'Hinch were playing with 14 men at this point due to the sin-binning of Lawton at the end of the first half, but they remained unfazed and as Ferris superbly broke through the stern Trinity
rearguard for an outstanding individual try on 48 minutes.
In the absence of Lawton, out-half Harry McAleese comfortably dispatched the conversion, meaning
that Trinity were once again having to play catch up.
Further indiscipline from Graham meant that Ballynahinch's hand was once again reduced though, and Trinity were rewarded on the hour mark when a powerful drive by their pack ended with second row Jack Kelly grounding the ball for hard-earned score.
The reliable Joyce, who was a more than able deputy for Irish underage international Cathal Marsh, brought his tally up to 11 points from the tricky conversion attempt, which set up the game for a tantalising conclusion.
Both sides probed to considerable effect during the final quarter, but even though a draw looked like a distinct possibility for large spells, Graham had other ideas.
The 'Hinch back rower drove over underneath the posts for the decisive score of the game. Lawton resumed kicking duties with a routinely struck conversion, which helped 'Hinch confirm their 13th league success from 15 outings.
With a game more played than the league leaders, Trinity's challenge for top honours now looks quite slim, but with a couple of crucial meetings to come, they are still well in contention for that crucial second spot.
Meanwhile, in the day's other game in Division 1B, Buccaneers hung on for a 39-22 win over Belfast Harlequins at Dubarry Park.
Jonny Holmes, Robbie Creighton, Michael Scholes and Roger Kirkwood all crossed for tries for 'Quins, who trailed by 25-0 after a Buccs-dominated first half.
But Alex Hayman's second try of the afternoon and another from captain Kolo Kiripati made certain of the victory for the midlands side.