Wycombe Wanderers winger Matt Phillips has joined Blackpool for an initial fee of £325,000.
The deal could be worth close to £700,000 if the Seasiders stay in the Premier League.
The second part of the fee will also be paid if Blackpool regain their top-flight status within four years if they are relegated and a sell-on clause has been inserted into the deal as well.
Blackpool manager Ian Holloway told his club's official website: "Matty has been on our radar for some time, he did well in the European Under-19 tournament for England in the summer and has played almost 80 league games for Wycombe, which at 19 is a real achievement.
"I can't wait for him to get involved in our system and work with him on the training ground."
Wycombe boss Gary Waddock was full of praise for the departing Phillips.
"It's a great opportunity for Matty to play in the Premier League and we couldn't stand in his way," he told the Chairboys' official website.
"He's an outstanding prospect and I'm sorry to lose him, but it's a great move for him and excellent business for the football club."
