The Brazilian started life at Vicarage Road in scintillating form, scoring three times in first seven appearances after arriving from Fluminese in the summer. And it's no coincidence that Watford's form has dropped off dramatically since the 20-year-old found himself in a rut.
But despite not finding the back of the net in eleven games, Prodl is confident the £8m striker will bounce back.
"He had an impressive start to his first Premier League season, of course, but we have to know he came straight from Brazil, he didn't have a long break in summer," said Prodl
"Also he is still a young player, [there will be] some games where he is not on top, he is a top player, he's always putting problems to the opponents so that's why they mark him even better now and also he might have a little struggle with tiredness.
"But he is one of our key players, we need him and he will get back on track, he will score, he will assist again.
"That's what we expect from him and that's what he expects from himself as well."