The Catalans have fallen behind Atletico Madrid in the title race but the coach is adamant they must not think about their fellow contenders if they want to succeed.
The Catalans head into the match on the back of defeat last weekend at home to Valencia, although they bounced back with a 3-1 win in their midweek Copa del Rey semifinal first leg against Real Sociedad.
Barca now sits second in the three horse race for the Spanish crown - ahead of Real Madrid on goal difference but behind Atletico Madrid - and Martino has stressed that the club must forget about teams around it and put all its energy into defeating Sevilla.
"The match against Sevilla is probably the most difficult we have left," the Argentine coach told reporters on Saturday. "It is crucial and will have hugely positive or negative impact on our future.
"We need to not think about [Atletico and Real Madrid] and focus on making ourselves stronger, thinking only about football. There's a long way to go in La Liga, still."