In 2002 he beat his fellow countryman Vassily Ivanchuk in the final of the FIDE World Championship 2002 by a score of 4 Â 1\/2 â `` 2 Â 1\/2 . This made him FIDE world champion at the age of 18 , the first teenager and youngest person to win this form of the title . In 2002 he beat his fellow countryman Vassily Ivanchuk in the final of the FIDE World Chess Championship 2002 by a score of 4 Â 1\/2 -2 Â 1\/2 to become FIDE world champion at the age of 18 , the first teenager and youngest person to ever become FIDE world champion .