Melbourne - South Africa's Kevin Anderson was upset by unseeded American Frances Tiafoe in the Australian Open second round on Wednesday.
The 20-year-old Tiafoe, who is ranked 39th on the ATP Tour rankings, shocked the fifth-seeded Anderson 4-6, 6-4, 6-4, 7-5.
Anderson had gone into the match holding a 3-0 head-to-head advantage against Tiafoe and was looking good leading by a set and 3-0 before his game started to unravel.
Anderson hit 50 winners but made an uncharacteristic 35 unforced errors.
Tiafoe, who is into the third round at Melbourne Park for the first time, next plays Italian veteran Andreas Seppi.
Meanwhile, South Africa's other participant in the men's singles, Lloyd Harris, suffered a heavy defeat at the hands of Russia's Daniil Medvedev in the first round on Tuesday.
In the men's doubles, South Africa's Raven Klaasen and his New Zealand doubles partner Michael Venus opened their campaign with a 4-6, 6-4, 6-3 win against American Bradley Klahn and Kazakhstan’s Mikhail Kukushkin.