|Date of birth||August 29, 1977|
|Place of birth||Rijswijk, Netherlands|
|Height||1.77 m (5 ft 9 1⁄2 in)|
|2002-2003||→ Aris (loan)||21||(1)|
|2003-2004||→ Heerenveen (loan)||32||(9)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 1 September 2011.
† Appearances (Goals).
In 1999, he was voted by Ajax supporters as Most Talented Player, receiving the Marco van Basten Trophy. The following year, he netted 15 league goals as a midfielder, but the club could only finish fifth.
A regular under Jan Wouters, Knopper saw his playing time reduce when Co Adriaanse took over as head coach in 2000, also being injured for almost the entire season, playing only eight matches that year, and appearing slightly more in the following, which would be his last.
In May 2002, Knopper had a trial with English Premier League side Sunderland and played in that predicament in the Niall Quinn testimonial match with the Republic of Ireland on the 14th. From 2002–04 he served two loans, first with Greece's Aris Thessaloniki F.C. then with SC Heerenveen, slightly reviving his career with the latter. Upon his Ajax release in the 2004 summer, he spent two additional seasons with Vitesse Arnhem, appearing regularly.
After some problems with Vitesse manager Aad de Mos, Knopper was forced to leave, joining ADO Den Haag. In July 2007, a three-year link was agreed, with the player netting again in double figures (10) in 2008–09, crucial to help in a narrow escape from relegation; in the 2010 summer, aged 33, he was released.
- "Sunderland 0 Republic of Ireland 3 (Niall Quinn Testimonial)". 1 Sunderland. 14 May 2002. Retrieved 9 March 2011.
- Ik heb veel geleerd bij Haaglandia, vooral van ex profs zoals Mourad Mghizrat, John van Otterlo en Richard Knopper”.