Martinez came off the bench and within 120 seconds had scored the decisive goal at the Tardini.
“I am happy because we got back to winning ways and that was important," the forward told DAZN.
“We are pleased, but are aware there are still things to sort out, so must keep working hard. Without doubt, we need to work on our mentality, as we were missing something over the last couple of games.
“These are three fundamental points to keep our distance from the chasing pack and hold on to fourth place. With the right results and mentality, we can get back into the Champions League."