The Black Cats have struggled throughout the campaign but recent results have seen them slip closer to the relegation zone in the Premier League.
Larsson told the Daily Mail: "It is a defining weekend, but you could have said that about the last few weekends and the ones coming up as well.
"If we lose, we will have no option to look below us in the table because defeat could see the bottom teams closing the gap on us. If we lose and those teams under us win, then we are right in the relegation mix."
Larsson has struggled to find the net for the Black Cats this season, scoring just once.