Serbia have drawn first blood in the first ATP Cup semi-final with Dusan Lajovic upsetting world No.17 Karen Khachanov in the opening singles rubber.

Lajovic backed up his straight-sets win over Canadian young gun Felix Auger-Aliassime on Friday with an even more impressive 7-5 7-6 (7-1) victory over a player ranked 17 spots spots above him.

The win leaves world No.5 Daniil Medvedev needing to upstage seven-times Australian Open champion Novak Djokovic to keep Russia in the best-of-three tie in Sydney.

Djokovic holds a 3-2 record against the 2019 US Open finalist Medvedev, who has won their past two encounters.

Australia play Spain on Saturday night in the second semi-final of the inaugural $22 million season-opening teams’ event.