The Black Cats went down to a 1-0 loss at the KC Stadium on Saturday to remain five points from Premier League safety after ten games.
They have collected just four points so far this season and Larsson knows their performances have not been good enough.
However, he is in no doubt that Sunderland will improve and stave off the threat of relegation.
"We are not kidding ourselves because we know where we are in the league," said Larsson.
"But, if you are asking me if we'll get out of trouble, then I'll say there is no question that we will.
"We are massively disappointed with this defeat. Our performance in the first half and the result were not good enough.
"I have no doubt we'll get out of this situation - it's a matter of when, not if.
"Our fans were fantastic and backed us all the way - all we can do is apologise for not picking up the points for them."