The Blues have begun the competition with a 100 per cent record after beating both Grenoble and Rovigo in October.
However, they have made a slow start to the GUINNESS PRO12, sitting ninth in the table after two wins from their opening nine games.
Saturday's visitors to BT Sport Cardiff Arms Park are also undefeated in Europe and Hammett believes playing in Wales will be a key factor in the outcome of the clash.
"Playing a team from a different country means there will be a different style and we need to make sure our patterns will work," he told Wales Online.
"You always hope that playing at home is an advantage. Playing at home, though, doesn't just get the job done. You have got to perform with passion and line speed, get from A to B quickly and do your job.
"We need clarity on that and that is critical because the atmosphere can add and enhance that. Playing at home is something we relish.
"There is no doubt that this game and the away game with London Irish will be very important in this competition. Both teams will know how important it is."
Sam Warburton is available after captaining Wales to an historic win over South Africa but Hammett has decided to rest him for the game this weekend.
"The next month is busy for us so to make sure Warby is 100 per cent we're better off holding him out of this one," he added.
"His mindset is just fantastic and he's up for this next month or so."
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