Worcester Warriors won Pool Three with a game to spare after beating Bucuresti Oaks 38-19 at Sixways while rivals Bourgoin slipped up in Italy.
Matt Powell scored twice in the final five minutes to finally shrug off a spirited display from the Romanians who recovered from 26-6 down to trail 26-19 in the 70th minute.
Ryan Powell looked to have set Worcester on course for an easy win inside 10 minutes.
But Florin Vlaicu converted twice to shake up the Warriors.
Chris Latham got the Warriors back on track and All Black Rico Gear followed, after a penalty try, to clinch a bonus point.
But Mike Ruddock's men almost paid the price for taking their foot off the gas as Bucuresti upset Sixways with Daniel Carpo's try before Powell steered Worcester home late on.