Barcelona will have a Champions League clash with Ajax Tuesday and Messi scored a hat-trick in Barca's 4-0 win when the two sides last met in September.
Martino recognized Messi's absence will be a boost for any side that faces Barcelona between now and his return, reported Xinhua.
However, he was still confident that Barca will get at least a point they need to guarantee first place in Group H.
"I have said already this week that without Messi we have lost the best player in the world and that always creates a difficulty. If I was on the other side I would see it as a positive, but the quality of the Barcelona squad means there can be no excuses," he said.