Boselli has yet to score for Wigan since his big-money arrival from Estudiantes this summer and he missed a gilt-edged chance to open his account in Saturday's draw with Sunderland.
However, Martinez is refusing to panic and he believes Boselli will prove his worth once he is fully fit.
"He's a finisher, he's a goalscorer and I've never seen him miss in that situation," said Martinez.
"The Argentinian league has completely different demands physically and he is getting used to playing here.
"He's reaching that level for 55 or 60 minutes and when he gets fully fit he will never miss those sorts of chances because that's his strength."