Jose Luis Mendilibar`s side are two points ahead of the drop zone with two games of the season left and, if results fall their way this weekend, safety could be assured.
If they win and either Real Zaragoza or Deportivo La Coruna lose - they have tough respective games against Real Betis and Malaga respectively - they are safe.
"All we are thinking about is the win," said Chile international midfielder Francisco Silva, suggesting results elsewhere do not matter to him.
"We know what the game means for the league. The responsibility is very big and that they (Zaragoza and Depor) have yet to leave. We will play to win as if our lives depend on it."
The 27-year-old, who is on loan from Universidad Catolica, is not feeling the pressure of the situation, though, and knows he and his team-mates will have backing from the stands.
"I am calm, in a period of calmness. A lot is at stake when we play but we play with player number 12, who will fill the stadium. They will support us.
"Since I arrived here, the support have helped us, supported us and given us the energy to compete in games.
"We know we are not able to lose, that we must not exit and not give anything away, play to the death for a victory which would mean we have more than a foot in the Primera Liga."
Osasuna will face a Sevilla side whose European hopes remain alive thanks to a complicated mess at the top of the table.
The top four places grant Champions League access while fifth and six carry a Europa League spot but, with Copa del Rey winners Atletico Madrid third, an extra Europa place will be available.
And, with Malaga, currently sixth and appealing their European ban, as low as eighth could get into Europe. Sevilla are ninth and have work to do, but Silva knows how tough a side they are.
"Sevilla are a very good team," he said. We have to score as quickly as possible and always go forward. Pressure and maintain our intensity through the game."
Silva has also spoken of the importance of captain Francisco Punal. The 37-year-old is one of the most experienced players in the division and Silva expects him to lead from the front.
"We all know what he always is and we all have to try to do what he does on Sunday."
For Sevilla coach Unai Emery, the message is a similar one.
"We are focused only on the game with Osasuna," he said.
"They have a good record at home and it is important we look after the objectives we have."