Icardi featured for Inter in yesterday's 0-0 draw with Atalanta.
But Cassano says: "Inter plays with a 4-2-3-1, which means having only one striker: Icardi cannot play with Lautaro. If it depended on Spalletti, he would play Martinez because he prefers strikers who play for the team.
"Lautaro did very well, he is 20 years old and has to play because he is stronger than Mauro. Icardi just scores, but if he (Lautaro) does not score he never takes it personally."