Brive are unbeaten in this year's competition, whilst Sale's only defeat came at the hands of their visitors back in Round 1.
And Mignardi knows his side need the performance to reach the last eight for a second year running.
"We know we need to be careful in the match," he said.
"Its going to be very tough - we are playing in England against a competitive team.
"Sale are a big side, they have got better and better since that first game and are playing well in the premiership.
"We know we have to be strong in defence and be disciplined to get the win.
"Obviously our goal is qualification. We know we need at least a defensive bonus point but we are going there for the win.
"If we qualify, it will be three more games before the title. Everything can happen.
If we do the right game at the right time we can get the title. It will be our goal if we reach the quarter-final."