Inter doesn't really depend on Martinez anymore, they already have Thuram.
If Lutaro Martinez have been absent against Atletico Madrid I don't think its big loss for Inter Milan and Simione Inzaghi will try other option as one striker only with his scheme.
Without Lautaro Martinez, it will be very difficult for Inter Milan to win against Atletico Madrid. Inter Milan is a strong team but the key player in their squad is Lautaro Martinez. Scored 15 goals and 2 assists in 16 matches in Serie A. In every match we have seen excellent gameplay from Lautaro Martinez. Atletico Madrid is not a weak team. They have talented players like Griezmann, Depay, Morata and Correa in their attack. And so defeating this team will not be an easy task at all. However, Inter Milan's defense is very strong. Therefore, the Inter Milan team is considered as the favorite in this match. However, if Martinez is in the squad for this match, I've decided to bet Inter Milan to win.
I agree that Lautaro Martinez is a key player and his absence would be a huge loss for the team, but they would still not be left without chances. What is so strong about Inter Milan this season is the stability within their team straight through from the defense to the offense. It would weaken their offense and hence the entire game, but it would still not be easy to score against Inter Milan and that is something they are even doing better this year than last year. But in the Champions League obviously you always want all the best players to be healthy and available.