Serbia's Novak Djokovic reacts during his semi-final match against Switzerland's Roger Federer at the Australian Open tennis tournament at Melbourne Park, Australia, January 28, 2016. [Photo/Agencies]

Picking off Federer's serve at will, Djokovic broke him twice and trounced him in the baseline rallies before closing out the set with a huge serve down the 'T'.

The horror show quickly resumed for the Swiss, who was broken in the third game to love and again in the fifth. The set lasted scarcely 30 minutes.

As the players returned to court, the crowd clamoured for a Federer comeback, and the Swiss rallied to pressure the Serb's serve in an epic sixth game.

Djokovic saved three break points but finally folded with a fourth as a net-rushing Federer forced a passing shot wide.

In the stands, Federer's wife Mirka could barely bring herself to watch as her husband laboured to serve out the set but Djokovic fired a forehand long to raise thunderous cheers from the terraces.

The weather turned in Djokovic's favour, with rain causing a delay to shut the stadium's roof and Federer's momentum was stalled.