And although there is mounting speculation the 20-year-old is attracting interest from Premier League clubs, Hornets manager Gianfranco Zola is confident he will still have the 18-goal hit man when the January transfer window closes.
Zola said: "I am not surprised that other clubs are supposed to be interested in him because he is a fine player with a great attitude.
"But he wants to keep on learning and I think he feels he is with the best club to do that at this stage of his career. We know that we can work with him and help him improve.
"There are still margins for him to work on but he is keen to do that because is a very good boy and works very hard. He has a great mentality."
Forest boss Alex McLeish was wracked with disappointment, particularly at his defence.
He said: "We were devoid of any ideas and legs and it was one of the worst defensive performances I've seen - it was a 'brain dead' performance.
"There needs to be a vast improvement because we won't get to the play-offs with displays like that. I didn't think Watford were extra special - just that we were very poor on the day.
"We know we can do a lot better than that so I've got to pick the players up on Monday.
"We also need some help in terms of bringing players in. We missed out on a player this week, which was disappointing, but it's clear that we need to strengthen."