Answer
Hasselbaink replaced Gianfranco Zola as the most expensive signing by Chelsea in May 2000. He was signed from Atlético Madrid for a fee of £15 million. Zola had been Chelsea's most expensive signing until then, having been signed from Parma for £14 million in 1996. Hasselbaink went on to become a key player for Chelsea, scoring 127 goals in 251 appearances for the club.