Following a 3-0 defeat to Manchester United last night, Villa sit three points above the relegation zone with just four matches left to play.
Lambert has challenged his players to respond and boost their survival hopes against Paolo Di Canio's rejuvenated side next Monday.
He told BBC Sport: "We've got to win it. Sunderland are going well themselves but it is an opportunity for us.
"We are at home. We know what we have to do and that's a good thing. We are getting better and I still think so many things will happen between now and the end of the season in that little group of teams at the bottom of the table.
"We have got a massive game on Monday night and we have to try and win it."
The Scot also insisted that he was "proud" of his team's battling display at Old Trafford despite their loss.