A last-gasp try from replacement winger Peter Sullivan gave Connacht a dramatic 26-24 victory over Ulster at the Kingspan in the Rainbow Cup's opening round.
Using the captain's challenge law introduced for this competition, Connacht, with their bench making a crucial impact, came back from what seemed certain defeat to work the winning score with the clock in red.
That was after Ulster appeared to have secured the spoils for themselves with a late Dave Shanahan try in this hard-fought Irish derby.
It was only the second time that Connacht have won in Belfast since 1960 and will have given a strong Ulster side, who had Iain Henderson back as well as long-term absentee Will Addison, a wake-up call ahead of next weekend's Challenge Cup semi-final at Leicester.
Scrum-half Caolin Blade scored twice in an eye-catching display from the Connacht number nine while, for Ulster, the return of Addison after over a year out also saw him look sharp.
Connacht skipper Paul Boyle opened the scoring for the visitors after seven minutes following some great multi-phase work with Jack Carty converting.
After Blade had a score ruled out for an apparent double movement - a call which could have resulted in the newly-trialled captain's challenge but was not utilised - Ulster got on the scoreboard after 23 minutes through Jacob Stockdale, who profited from John Cooney's long pass.
The scrum-half failed to convert from the touchline, though.
It was all Ulster now and just before the half hour, soon after Nick Timoney was held short of the line, the home side put a penalty into the corner with Rob Herring dotting down from the maul to put Dan McFarland's side in the lead.
Cooney also converted to put Ulster 12-7 ahead and there were no further scores in a frenetic first half with both sides throwing everything into attack.
Ulster claimed their third try just four minutes into the second half, Billy Burns getting over in the corner after a superb break by James Hume nearly put Cooney away, though that led to Carty's yellow card for a deliberate knock-on.
Cooney missed the difficult conversion but Ulster were now 10 points in front.
Connacht, despite being down to 14 men, struck back however and after a powerful run from impressive replacement Abraham Papali'i, Blade scorched over with Tom Daly converting.
Connacht then came again with Blade wriggling over from close range after Ultan Dillane was held short. Daly converted and the westerners now led 21-17.
But, in a dramatic finish to the match, Ulster reclaimed the lead when replacements Michael Lowry and Shanahan combined with the latter crossing in the 73rd minute for a try that was converted by Lowry.
There was still another twist in the tale, however, and Connacht snatched victory at the death when Sullivan, with a penalty coming, pounced on a grubber after the visitors had used their captain's challenge in the closing moments.