Michael Johnson led the tributes to Wayde van Niekerk on Saturday after the South African made sprinting history in Bloemfontein.
By running a time of 9.98 seconds to win the 100 metres final at the Free State Championships, Van Niekerk became the first man to break the 10-second mark in the 100m, the 20-second barrier in the 200m and the 44-second mark in the 400m.
Johnson, the owner of the 400m world record who also held the fastest time over 200m prior to Usain Bolt setting a new best in 2008, expressed his admiration for the achievement on Twitter.
The legendary American posted: "Sub 10, sub 20, sub 44. That's crazy. Great things could be ahead for @WaydeDreamer."
Van Niekerk uploaded a video of his 100m race to Instagram, adding the caption: "Wow!!! Truly grateful and humbled by the opportunity and talents the Lord has blessed me with. Finally reaching my childhood dream of sub 10."
Despite his impressive performance over the shorter distance, Van Niekerk is set to focus solely on the 400m at this year's Rio Olympics - having claimed gold in that event at the 2015 world championships in Beijing.