The Black Cats head to Stamford Bridge on Saturday afternoon looking to recreate their famous win in 2014, which kept them up in that campaign.
They are in desperate need of a win to stay in with a chance of avoiding relegation as the survival race goes down to the wire.
Sunderland are currently 18th in the table, with last weekend’s draw against Stoke City seeing rivals Newcastle United move above them in the table.
The fight is far from over though, and Larsson has insisted that keeping their nerve is the key thing for them.
“The main key is about holding your nerve and being able to handle the pressure,” he told safc.com.
“In every game the pressure is high and you can’t try and repair anything later on. It’s now or never.”
Whether Sunderland can avoid the drop remains to be seen, with this Premier League season proving to be an unpredictable one to say the least.
Many had backed them to stay up because they have Sam Allardyce in charge, but he has struggled to get the wins on the board despite positive performances from them.
Worse is the fact that Newcastle United have started to pick up wins under Rafa Benitez to make it more difficult for them.