Australian Bernard Tomic secured a massive upset by beating world No.1 Novak Djokovic 6-4 6-4 in their Hopman Cup tennis clash in Perth on Wednesday night.

Tomic was at his sizzling best during the straight-sets romp, unleashing a flurry of winners to notch his second career win over Djokovic and give Australia a vital 1-0 lead over top-ranked Serbia in the mixed-teams event.

The 20-year-old Queenslander entered the match having lost all three of his ATP matches against Djokovic, including their quarter-final stoush at Wimbledon in 2011.

Tomic did get one over Djokovic in a light-hearted exhibition match at the Kooyong Tennis Classic in 2010.

But his latest victory marks a significant step forward in Tomic’s development as a future world beater.

Tomic, who has slipped to a ranking of 52 after reaching a career-high of 27 last June, frustrated Djokovic during an entertaining opening set.

Djokovic had to save four break points in his first service game, and even had his plea for a change of balls approved after complaining they were too soft.

But the 25-year-old couldn’t repeat the feat in the ninth game, with three scintillating winners from Tomic securing the crucial break.