Pool 5 contains a cosmopolitan blend of two French clubs - La Rochelle and Agen - Gloucester Rugby and Femi-CZ Rovigo with La Rochelle just a point clear of Gloucester and Agen with two wins apiece in a three- way race for qualification.
"It is only a job half done and Sunday is huge for us," said head coach Bryan Redpath.
"The big thing is the result over at La Rochelle means we have given ourselves a chance to be in the mix to win the group.
"Now Sunday's return game represents the next match and hopefully another step towards the opportunity to win a trophy and get to the Heineken Cup for next season.
"Those are two huge incentives for Gloucester."
While Gloucester were winning in France, Agen were doing what they had to do in Italy with a 33-10 try bonus point win in Rovigo.
Gloucester went down 26-19 in Agen in Round 1 and Redpath admits "we got a point over there but we really should have done better.
"However, we learnt a lot from that defeat and when we went ahead at La Rochelle those lessons stood us in good stead because our discipline was key to getting the win.
"In fact we are learning a fair bit from playing in the Amlin Challenge Cup and really enjoying the experiences the tournament provides."
One of the lessons Redpath is keen for his players to take on board ahead of the return on Sunday is to react immediately to what they see in front of them.
"It is never easy going to France and winning and I admit our first half was a bit shaky and it took us some time adapting to what they came out with - after studying their matches before the autumn internationals they surprised us in that they went for a pretty expansive game.
"What we cannot do is go 40 minutes before reacting to what the opposing team come up with because our second half performance was great.
"After losing at home we know they will come out and throw everything at us on Sunday and, once again, we are expecting the unexpected.
"I was delighted with our set piece play, we were very strong in both scrum and line-out, and we will need to repeat that at Kingsholm.
"At La Rochelle their game plan was very expansive - and that is good to see - while they also have plenty of big men so potentially they have the chance of being very direct and physical and we will expect more of the same on Sunday."