Ronaldo scored 450 goals in 438 appearances for Los Blancos between 2009 and 2018 before leaving for Juventus, but the attacker is yet to get off the mark in Serie A.
Martinez has claimed that Madrid will find it difficult to individually replace Ronaldo, but has said that the European champions "will be fine" due to the overall strength of their team.
"We all know what Cristiano has given Real Madrid," Martinez told Goal.com. "All of those goals over the years will be difficult to match by a single player, but we are watching a different Madrid and there are the results. They are doing well.
"I was with [Julen] Lopetegui in the national team and he's a great coach. Surely they will be fine. But we always give it all against Real Madrid in San Mames. It is our party. We all want to win."
Lopetegui's side will return to action after the international break with a trip to Bilbao on September 15.