The Sportsground witnessed another night to remember as Connacht fought back from a 10-point interval deficit to defeat four-time European champions Toulouse 23-21 in Pool 2.
Craig Ronaldson's coolly-struck conversion of Bundee Aki's 67th-minute try proved to be the decisive score, as Toulouse fell to a fifth successive away defeat in Europe for the first time in their history.
The French giants' raw power saw them open up a 21-11 interval lead, Sebastien Bezy's three early scrum penalties topped up by tries from Yann David and Jean-Marc Doussain.
In between, Connacht had recovered from their sluggish start to set up Niyi Adeolokun's fourth try of the season, with Jack Carty also kicking two penalties.
Back in Europe's top tier for the first time since 2013/14, the westerners went on to punish tiring Toulouse with back-to-back tries from full-back Tiernan O'Halloran and the talismanic Aki, whose centre partner Ronaldson nailed the all-important conversion.
After a superb scrummaging display against Clermont Auvergne last week, Toulouse brought that set-piece strength to Galway with Bezy rewarding his forwards with three penalty goals inside 13 minutes.
Two lineout steals from Andrew Browne and Ultan Dillane got Connacht firing towards the end of the first quarter, Cian Kelleher sidestepping through before prop Finlay Bealham was stopped short of the line.
Pat Lam's men were over just a couple of minutes later, Dillane's leap setting up a thrilling back-line move spearheaded by Ronaldson and Aki. Possession was retained and winger Adeolokun was sent over in the right corner.
Carty missed the difficult conversion but nailed a right-sided penalty in the 25th minute, and the home pack went close to scoring from a maul before Carty knocked over his second successful kick for 11-9.
Bezy sent a difficult long-range strike wide of the posts after Connacht tighthead Conor Carey was warned for his angle of scrummaging. He also missed the conversion of David's 34th-minute try, the strongly-built centre scoring in the left corner despite the presence of three Connacht defenders.
Even better followed two minutes later for the small pocket of visiting fans, Toulouse's offloads sticking and a free-flowing move full of flair ending with fly-half Doussain driving in under the posts.
Having turned down three points on the stroke of half-time, Connacht blundered at the ensuing lineout and Carty also missed the first place-kick of the second half.
The gap remained at 10 points after an equally poor kick from Bezy at the other end. The PRO12 champions, though, found another gear closing in on the hour mark, O'Halloran cutting inside Gael Fickou to finish off Carty's long pass.
Although the tough conversion proved beyond Carty, O'Halloran, Kelleher and Ronaldson all continued to bubble with intent in the back-line. They were aided by the timely impact off the bench of Kieran Marmion - the man-of-the-match from Connacht's famous 2013 win in Toulouse - and the strong-carrying Sean O'Brien.
In a grandstand finish, Connacht kept grinding their way up into the Toulouse 22. Ugo Mola's side were looking sluggish and Aki surged over thanks to a big hand-off on Talalelei Gray.
The raucous home crowd erupted when Ronaldson curled over a peach of a conversion and with Toulouse's error count increasing and a vital 73rd-minute scrum holding firm for Connacht, they deservedly held on in breathless fashion.
Next up for Connacht is a trip to hapless Zebre who were beaten by a competition record scoreline of 82-14 today by Wasps.