Ulster moved momentarily seven points clear in Pool 5 but failed to secure a try bonus point in their 27-16 win over Montpellier.
Tries from Robbie Diack, Ruan Pienaar and John Afoa helped a scrappy Ulster seal the win.
Although missing a plethora of first time regulars, the French side put in a sterling performance, and were terribly unlucky not to have gained something from this encounter.
The visitors competed every step of the way through the boot of scrum-half; Eric Escande, and a well taken try by Robins Tchale-Watchou.
The hosts just about deserved the win, but will be desperately disappointed not to have secured maximum points in a group that seems destined to go to the wire.
It was an intensely physical start for the home team, and their efforts earned Ulster an early turnover.
Pienaar had a good chance to open the scoring on three minutes, but missed his kick. Escande made no mistake for the visitors on seven minutes however, when he nailed a superb penalty to make it 0-3.
Despite their changes, Montpellier were competing ferociously at the breakdown from the outset and put the hosts under severe pressure. Escande had another opportunity to extend his side's lead on 15 minutes, but was off target with his strike.
The Top 14 side had certainly come to play, and were unlucky not to be further ahead after the first 20 minutes.
It was Ulster that crossed the whitewash first, when a beautifully aimed cross-field kick by Jackson saw Diack lingering on the left wing. The South African blindside duly grounded the ball, but the TMO was needed to determine that the try was good. Pienaar converted to make it 7-3.
Things got even better for the hosts when Pienaar swept up a stray ball yards from the Montpellier line to score again. The scrum-half converted to make it 14-3 to the home side.
But the Frenchmen struck back fantastically on the 30-minute mark when Charles Geli burst through a gap in the home defence before putting Tchale-Watchou away under the posts.
Pienaar earned respite for Ulster five minutes later, increasing the gap to seven, only for the visitors to narrow the deficit again on the 40-minute mark when Escande coolly slotted another penalty to make it 17-14 at half time.
Pienaar, named Man of the Match, gave the Irish province the perfect start to the second half by landing another penalty to make it 20-13 - with Escande responded in kind.
As hard as they tried, Ulster were unable to break down their French opponents. Eventually their moment came from the unlikeliest of sources.
Kiwi prop Afoa picked up a loose ball inside the visitors' 22 and cantered determinedly under the posts. The Ravenhill men were now within a whisker of that crucial try bonus point.
Pienaar almost delivered that on 67 minutes when he charged down a kick from Pierre Berard and seemed to have touched down, but was held up over the line. The visitors' scrum was beginning to achieve some ascendancy over the Irish side.
With the group so tight, there was now a desperate sense of urgency for the home side. They frantically threw the kitchen sink at Montpellier, but time and again were repelled by the French rearguard.
And despite Ulster's efforts, the visitors succeeded in denying the Ravenhill men that desired fourth try.
Ulster secured the much needed win, but tremendous credit must go to Montpellier for a laudable performance.
After their recent travails in the Top 14, this effort would have been a timely fillip for them. While Ulster will be relieved with the win, they will be praying that the lack of that bonus point doesn't prove too costly.
Tries: Diack, Pienaar, Afoa
Cons: Pienaar 3
Pens: Pienaar 2
Try: Tchale Watchou
Pens: Esconde 3
Ulster: 15 Jared Payne, 14 Andrew Trimble, 13 Darren Cave, 12 Luke Marshall, 11 Craig Gilroy, 10 Paddy Jackson, 9 Ruan Pienaar, 8 Nick Williams, 7 Chris Henry, 6 Robbie Diack, 5 Dan Tuohy, 4 Johann Muller (c), 3 John Afoa, 2 Rory Best, 1 Tom Court.
Replacements: 16 Rob Herring, 17 Callum Black, 18 Declan Fitzpatrick, 19 Iain Henderson, 20 Roger Wilson, 21 Sean Doyle, 22 Paul Marshall, 23 Michael Allen.
Montpellier: 15 Anthony Floch, 14 Yohann Artru, 13 Anthony Tuitavake, 12 Thomas Combezou, 11 Lucas Dupont, 10 Enzo Selponi, 9 Eric Escande, 8 Johnnie Beattie (c), 7 Alexandre Bias, 6 Kellen Galletier, 5 Robins Tchale Watchou, 4 Mickael Demarco, 3 Maximilliano Bustos, 2 Charles Geli, 1 Na'ama Leleimalefaga.
Replacements: 16 Thomas Bianchin, 17 Mikheil Nariashvili, 18 Paea Fa'anunu, 19 Mickael Ivaldi, 20 Fred Quercy, 21 Benoit Paillaugue, 22 Pierre Berard, 23 Timoci Nagusa.
Referee: Wayne Barnes (Eng)
Assistant referees: Tim Wigglesworth, Stuart Terheege (both Eng)
TMO: Sean Davey (Eng)
by Rory McGimpsey