Anelka faces his old club with Chelsea this weekend in a huge game for both teams.
Keown told the Daily Mail: "He is the best 17-year-old I have seen in my life and he is now fulfilling his potential in a Chelsea shirt.
"I remember a match at the end of the season against Derby. We went 1-0 down. Paul Merson went off sick, Tony Adams was sent off and we were down to nine men. We won 3-1 because every time anyone got the ball they gave it to Anelka. He was unbelievable. He's also a great lad, even though he was shy at first."