"When you can beat a side of Stade Francais' quality, it gives you a massive amount of confidence for future games," said Deacon.
"We haven't won the European Cup, or anything for that matter, for three or four years, and we are definitely looking to win some silverware this season.
"We will be going to Clermont to get a win, even though we know we may only need a point to win the pool. It would be a disaster if we went there and lost and didn't qualify.
"We know it is a hard place to go, and the temperature will be pretty cold, but we will be ready for another big effort."
Meanwhile, Leeds coach Daryl Powell has expressed his delight after the Tykes were awarded maximum points following last weekend's postponed clash against Calvisano.
The decision, made following a European Rugby Cup board meeting in Dublin, means Leeds are now level on points with Pool Two rivals Cardiff Blues and have an outside chance of reaching the quarter-finals.
The Calvisano game, originally due to be played last Saturday, was called off by referee George Clancy due to a frozen pitch at Centro Sportivo San Michele.
He then declared the surface fit some 24 hours later, but Leeds refused to play, believing the pitch was still unsafe.
Calvisano though, will now face misconduct complaints from the ERC disciplinary officer for failing to prepare a suitable venue for last Saturday's game and also refusing to fulfil a rescheduled fixture when directed by ERC.
"All week, we have been trying to put the situation to the back of our minds, but it was always a concern ahead of Sunday's match as to whether we would still be able to qualify," said Powell.
"We are obviously delighted with the decision by the ERC board to uphold our concerns about the safety of the Calvisano pitch, and now we can look forward to the challenge ahead of us on Sunday.
"This will be a massive game for both ourselves and Cardiff. We have been given plenty of challenges already this year, and this is another big one.
"We have got an opportunity to reach the quarter-final of the European Cup, and thankfully we now know exactly what we have to do to give ourselves the best shot at that."