Head coach Griffiths believes the trip to Bourgoin will almost certainly shape the outcome of the group but insists his players will accept nothing less than top spot after the disappointment of finishing runners-up last season.
"This season there is an air of unfinished business about this competition within the player group. We all want to go one better than we did at Kingsholm," he said.
"If we are going to have a split, in terms of home and away games, it's certainly better to have your last three games at home and we will look to take full advantage of that.
"We're all aware of how tough it's going to be in Bucuresti but we do hope that we don't encounter freezing conditions and a water logged pitch conditions by playing it a different time of year this season.
"With all due respect to our first two opponents, we should come away with two wins and it will set us up for the two games with Bourgoin on consecutive weekends which will almost certainly determine the future of us both.
"We all fully understand the value of home advantage and we want to play the quarter-finals and semi-finals here at Sixways Stadium. We want to emulate last season by finishing in the top two seeds and guaranteeing this again.
"After all the trials and tribulations, to finish top seeds in the second tier of European qualifying last season was a fantastic achievement by the players and we plan to repeat that this year."