<P> Lleyton Hewitt is both the youngest world No. 1 ( 20 years , 268 days ) and youngest year - end No. 1 , while Rafael Nadal is the oldest year - end No. 1 ( 31 years , 211 days ) . Roger Federer is the oldest No. 1 ( 36 years , 314 days ) . </P>
<P> Lleyton Hewitt is both the youngest world No. 1 ( 20 years , 268 days ) and youngest year - end No. 1 , while Rafael Nadal is the oldest year - end No. 1 ( 31 years , 211 days ) . Roger Federer is the oldest No. 1 ( 36 years , 314 days ) . </P>
who become the oldest atp world number one
who become the oldest atp world number one
Roger Federer
Roger Federer