Ulster moved level on points with Stade Franšais at the Pool 4 summit thanks to a 21-13 victory over familiar foes Edinburgh at a windy Ravenhill.
The Northern Irish had met their visitors twice already this term in what turned out to be losing Magners League and European games. But they were on the mark this time around with a clever 80-minute performance that put an end to their poor run of form against Rob Moffat's charges.
As mentioned, it was a game playing in atrocious conditions and it was Ulster's smart tactics that better combated both the weather and their rivals.
Edinburgh did have the strong wind at their backs in the first period but it was the confined approach from the hosts that frustrated the Scots, who only went in 5-6 up thanks to Chris Paterson's boot.
Co-leaders Stade will host already-eliminated Bath on Saturday and remain favourites to progress, while Ulster must beat Bath in their final group contest next week and hope for the French side to slip up against Edinburgh.
It was extremely difficult for Ulster to make any inroads early on, even when visiting tighthead David Young was sin-binned for seemingly pulling down a maul. In fact, it was Edinburgh who took the lead soon after Young returned when Paterson nailed a penalty after Ulster strayed offside.
Ulster responded, sparked by a break from man-of-the-match Isaac Boss. The forgotten Ireland scrum-half took a quick tap to himself in Ulster's territory and burst upfield before Stephen Ferris cleaned out just as Boss was beginning to look isolated. Lock Dan Tuohy was then on hand to charge upfield releasing centre Darren Cave who fixed the Edinburgh defence, straightened and got over the line.
Humphreys, into the teeth of the gale, failed to add the extra and Ulster surrendered the advantage immediately when Tuohy dropped the restart.
Paterson's second penalty seemed scant reward for having the conditions at their backs as the sides trooped off at the break with the visitors holding their one-point lead after ending the half camped on Ulster's line. It was all set up for Ulster to end that losing run.
The hosts' cause seemed further boosted when, with the conditions now at his back, Humphreys slotted an early penalty to give his side a two-point lead at 8-6.
But Edinburgh, with forward Roddy Grant leading the charge, crept their way back under Ulster's posts only for some last-ditch defending from Boss to help relieve the pressure.
Indeed it was a long kick out from Boss in his own 22 that led to Ulster's second try. Andrew Trimble's tackle on Nick De Luca led to a series of scrums the last of which saw Trimble take the ball on for Boss to collect, dummy the cover and dash in under the posts.
Five minutes after Boss's score, Ferris found himself in the bin for persistent infringing.
But unlike Ulster in the first half, the visitors took immediate advantage of the situation and moved the ball at pace for winger Jim Thompson to step inside for a score. Paterson converted to bring Moffat's side within two points with a nervy finish in prospect.
The next score was critical and it came courtesy of an in-form Trimble whose carry into contact saw Scott Newlands penalised. Humphreys did the honours with the three pointer just as Ferris rejoined the action.
All that remained was O'Connor's last-minute penalty as Ulster's European hopes remained alive at the expense of Edinburgh's.
Man-of-the-match: An early injury scare to Stephen Ferris had home and also Ireland supporters holding their breath before the flanker ran off the problem. The Lion was once again immense but his number nine was better. Hats off to Isaac Boss who put in a gutsy performance that was rewarded with a well-taken try.
Tries: Cave, Boss
Pen: Humphreys 2, O'Connor
Pen: Paterson 2
Ulster: 15 Jamie Smith, 14 Andrew Trimble, 13 Darren Cave, 12 Paddy Wallace, 11 Simon Danielli, 10 Ian Humphreys, 9 Isaac Boss, 8 Chris Henry (capt), 7 David Pollock, 6 Stephen Ferris, 5 Ed O'Donoghue, 4 Dan Tuohy, 3 BJ Botha, 2 Nigel Brady, 1 Tom Court.
Replacements: 16 Andy Kyriacou, 17 Bryan Young, 18 Declan Fitzpatrick, 19 Ryan Caldwell, 20 TJ Anderson, 21 Cillian Willis, 22 Niall O'Connor, 23 Timoci Nagusa.
Edinburgh: 15 Chris Paterson (capt), 14 Jim Thompson, 13 Ben Cairns, 12 John Houston, 11 Tim Visser, 10 Phil Godman, 9 Greig Laidlaw, 8 Roddy Grant, 7 Alan MacDonald, 6 Scott Newlands, 5 Jim Hamilton, 4 Scott MacLeod, 3 Davey Young, 2 Ross Ford, 1 Allan Jacobsen.
Replacements: 16 Andrew Kelly, 17 Kyle Traynor, 18 Geoff Cross, 19 Craig Hamilton, 20 David Callam, 21 Ross Samson, 22 Nick De Luca, 23 Mark Robertson.
Referee: Christophe Berdos (France)