Cape Town - South African tennis star Raven Klaasen and his New Zealand doubles partner Michael Venus have qualified for the last-four of the ATP Finals in London.
The fifth-seeded pairing beat second seeds Lukasz Kubot (Poland) and Marcelo Melo (Brazil) 6-3, 6-4 on Tuesday night to claim their second win of the event.
In their first match on Sunday, the SA-Kiwi duo beat fourth seeds Rajeev Ram (America) and Joe Salisbury (Great Britain), also with a 6-3, 6-4 scoreline.
Klaasen and Venus will face eighth seeds Ivan Dodig (Croatia) and Filip Polasek (Slovakia) in their final round-robin game on Thursday but are already assured of a spot in the weekend's semi-finals.
"Everything seems to be going great this week. We just keep trying to work hard and persevere together," Venus told the ATP Tour's official website. "We're just happy to be playing this well at the end of the year and especially in London. It's such a special event... The atmosphere makes it awesome to play out here."
Klaasen added: "We're really excited about how we played. Mikey carried me out there today. We're just happy to be through."
Results on the third day of the ATP Finals at London's O2 Arena on Tuesday (x denotes seeding):
Group Bjorn Borg
Roger Federer (SUI x3) bt Matteo Berrettini (ITA x8) 7-6 (7/2), 6-3
Dominic Thiem (AUT x5) bt Novak Djokovic (SRB x2) 6-7 (5/7), 6-3, 7-6 (7/5)
Group Jonas Bjorkman
Rajeev Ram/Joe Salisbury (USA/GBR x4) bt Ivan Dodig/Filip Polasek (CRO/SVK x8) 3-6, 6-3, 10-6
Raven Klaasen/Michael Venus (RSA/NZL x5) bt Lukasz Kubot/Marcelo Melo (POL/BRA x2) 6-3, 6-4