Watford forward Amin Nabizada has signed a four-and-a-half-year contract with the Championship club.
The 18-year-old made his senior debut as a late substitute in their 4-1 FA Cup defeat by Fulham in January.
He was sent on for the first time in the league in the 72nd minute against Leeds United the following month.
The England Under-18 international has yet to make a first team appearance this term but he said: "When I've talked to the club they've spoken really highly of me, and now I want to pay back that trust and produce on the pitch.