Kilkenny's unbeaten run also came to a halt in Division 2A, but Tullow in Division 1B and Wexford Wanderers in Division 3 continued their unbeaten starts, while Railway Union returned to winning ways to extend their lead at the top of Division 2B.
It was Wanderers hooker Henry Parker that delivered the injury-time coup de grâce in the 19-16 victory, after the visitors had battled back from an eight-point deficit with 10 minutes remaining to draw level.
Parker had kicked three first-half penalty goals to nudge his side 9-8 in front at half-time before out-half Fergal Campion scored a try for the rugby HQ side five minutes after the resumption that extended the lead to eight points when Parker added the extras.
Winger Conor Molloy had scored Tullamore's first-half try and the visitors seemed all set to share the spoils when centre David Clavin touched down with a little over five minutes on the clock.
Cue Parker's late theatrics that have given the chasing pack and Newbridge in particular (although their home game against Garda was off due to a bereavement) a glimmer of hope.
Tullamore will try to bounce straight back when they host Dundalk in Spollanstown tomorrow evening, with their visitors fresh off a confidence-boosting 20-3 home win over struggling Cill Dara.
The Co Louth side will be going for their third win in a row and they proved to be obstinate opponents for the league leaders when the two met in Mill Road back in September.
Newbridge's game against Garda has been rescheduled for December 22 in Rosetown, but the Co Kildare club face a tricky encounter in Coolmine tomorrow, especially as the Dublin club bagged a four-try bonus point in their excellent 22-16 win in Enniscorthy at the weekend.
If Newbridge are to apply any pressure to the leaders, they must win at Ashbrook tomorrow and then follow it up with five points against Garda.
Garda are at home to Wanderers and it's difficult to see anything other than a mauling for the hosts, while the clash of Enniscorthy at Cill Dara is a game between two sides that need to snap out of downward spirals.
Winger Sean McCarthy's try five minutes before half-time proved to be the decisive score in Tullow's 5-3 home win over third-placed Wicklow at a wet, windy and cold Black gates on Sunday.
The victory extended Tullow's lead at the top of Division 1B to 10 points as second-placed Monkstown had lost 18-15 in Ashbourne on Friday night.
At the other end there would appear no way back from relegation for Co Carlow following their 26-5 loss in Longford. The leading pair are both in action tomorrow as Tullow travel to Portarlington while Monkstown are at home in Sydney Parade to Longford.
In Division 2A, second-placed Malahide won 23-16 at home in Estuary Road against Kilkenny to close the gap at the top to a single point. The Dublin side visit Mullingar tomorrow while Kilkenny are at home to Gorey on Sunday.
Railway Union now lead Division 2B by eight points after their 29-5 home win over Athy.
On Sunday they travel to North Kildare, while Wexford Wanderers, who beat Rathdrum 43-10 at home on Friday night to open up an eight-point lead in Division 3, travel to Tallaght on the same day.