South Africa’s Raven Klaasen and his New Zealand partner, Michael Venus, were knocked out in the quarter-final of the men’s doubles at the Australian Open tennis tournament in Melbourne.

The unseeded Leonardo Mayer of Argentina and Portugal’s Joao Sousa beat the sixth seeds in straight sets — 6-4, 7-6.

Meanwhile, 20-year-old Stefanos Tsitsipas of Greece has reached his first Grand Slam semi-final.

The 14th seed beat Roberto Bautista Agut of Spain 7-5, 4-6, 6-4, 7-6 to reach the last four.