The Spain forward has scored three times in six La Liga games already this season, but is likely to miss the clash with a hamstring injury.
But Marcelino has faith in the likes of Manu del Moral and Frederic Kanoute to take the attack to the visitors.
"I am not worried," he told the club's official website.
"I sleep well at night. It's a situation when the competition started that we knew we would have, so it's not worth lamenting.
"It would be foolish to be here crying over the situation. We have the potential to win against Sporting.
"We must approach the game with positivity.
"We must show that we have more desire to win than them and that we are superior. If we do, we will be on the way to a satisfactory result."
Sevilla have struggled for goals of late, with just two in their last four matches, both scored by Kanoute.
Their defence has been superb, though, not conceding a single goal in that run to leave the side just two points off leading duo Barcelona and Levante.
Sporting would appear to pose little danger of ending that streak, rooted to the foot of the table and with just two league goals to their name.
They have taken just one point from their opening six games and were hammered 4-0 by Atletico Madrid in their last away game.