The Black Cats earned a point with ten men against Stoke City on Monday.
Mignolet said: â€śWhen youâ€™re 1-0 down with 10 men, you have to have courage and the mentality to come out in the second half and press and push on. Thatâ€™s exactly what we did.
â€śWe showed we all care and are up for the fight and now we have to do it again on Sunday. Itâ€™s imperative we do.â€ť
Mignolet revealed some of his team-mates were fearing the worst when Gardner saw red for a reckless tackle on Charlie Adam.
He added: â€śAt half-time, you look around the dressing room and obviously a couple of the ladsâ€™ heads were down. But the gaffer gave us a lot of confidence and we went back out and really worked hard.
â€śThe crowd were our 11th man in the second half and if they help us through again this weekend, I think we can win those three points and get ourselves secure.â€ť