Novak Djokovic stunned by Daniil Medvedev at ATP Finals in London

Novak Djokovic will face Alexander Zverev in a straight shootout for a place in the semi-finals of the ATP Finals after Daniil Medvedev crushes the world No 1 in 81 minutes at London's O2 Arena - making just 12 unforced errors in a red-hot performance