Novak Djokovic joins Roger Federer in ATP semi-finals
Novak Djokovic joined Roger Federer in the last four at the ATP World Tour Finals with victory over Tomas Berdych in London.
The world number one required just one set to qualify and won his final group match 6-3 7-5.
Federer had already won the group but earlier maintained his 100% record with a 7-5 4-6 6-4 win over Kei Nishikori.
Djokovic will face Rafael Nadal in Saturday’s semi-final, before Federer takes on Andy Murray or Stan Wawrinka.
The British number one and the Swiss number two will play for the remaining semi-final place at 20:00 GMT on Friday.