Rashford, 27, has started to rediscover some form since joining Barcelona on loan from Manchester United during the summer transfer window.
The Englishman is averaging a goal or assist every 88 minutes on average so far this season, assisting four and scoring three in just 616 minutes and has played his way back into Tuchel’s plans.
Tuchel still believes Rashford has work to do, however, urging the forward not to waste his potential and become one of the best in the world.
"He can be one of the best in the world because the finishing and the quality I see in training, with both legs and his head, he is explosive, he is fast, he is strong in the air, so for him there are no limits," Tuchel said ahead of their clash with Latvia on Tuesday.
"But the numbers don't reach the potential. He needs to push himself with goal involvement. He knows that from me.
"I think he still has to make these decisions. He is still young enough to make these decisions, because otherwise he might be disappointed in 10 years with what he could have been and what he may have done.
"That is the headline for him, to keep pushing himself to the limit. And the limit for him is very, very high, maybe higher than it is for others.
"He has this potential. But potential is a dangerous word with high-level sports, because you have to reach your personal best on a regular basis - that is demanded on this kind of level and that is the challenge for him. It is not a question of talent.
"It is a question of whether he can prove the point at club and international level; this is his task. If he starts fast or if he comes off the bench, he has to constantly prove himself."