Youngest person ranked world tennis number one (male)
- Who
- Marat Safin
- Where
- Uzbekistan (Tashkent,)
- When
- 18 September 2000
The youngest man to be ranked world tennis number one is Marat Mikhailovich Safin (Russia, b. 27 January 1980), who was aged 20 years 234 days when he achieved the position by winning the President's Cup Tournament in Tashkent, Uzbekistan on 17 September 2000.
His number one ranking was officially recognized when the ATP-Tour Champion's Race rankings were issued on 18 September 2000.