The Belgian made his return from injury as a substitute against Manchester United last Sunday.
According to Tuchel, the powerful striker could have a more significant role when Chelsea travel to Vicarage Road.
Asked about Lukaku's progress, Tuchel told reporters: "Romelu is pretty easy.
"He came on in the last match and he has continued to train with the group.
"He is ready to progress in minutes and this is where he is at right now."
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