The Argentina international was particularly impressive at Fulham, capping a fine display with a fierce strike that secured his side a point.
"It was special," Martinez said. "Strikers are always going to be judged on clinical finishes and what they do in front of goal.
"Franco deserves a special mention for the contribution he has given to the team against Fulham.
"To have a striker with the generosity in his work is difficult to find in the modern game and I was very pleased with the way he worked hard for the team.
"Then the way he found the back of the net was a special, special strike and I think it had to be that way with the home goalkeeper's form.
"Franco can, though, be that clinical finisher, with the right, the left and good in the air. He is a special, special striker and I am glad he got the reward for all the hard work he put in."