World number two Novak Djokovic raced into the last four of the China Open in straight sets yesterday as home favourite Li Na set up a testing women’s semi-final with Maria Sharapova.

The 25-year-old Serbian thumped Jurgen Melzer 6-1, 6-2 to maintain his unbeaten record at the Beijing tournament and continue his push to finish the year at number one in the rankings.

Djokovic, behind only Roger Federer in the ATP standings, has won the China Open on the two occasions he has entered – in 2009 and 2010 – but missed last year because of injury.

The number one seed made light work of Melzer, winning in just 53 minutes, to set up a semi-final clash with Germany’s Florian Mayer, who beat wildcard Zhang Ze to bring the Chinese wildcard’s fairytale run crashing to a halt.

The 22-year-old, ranked 165th in the world, made history in the last 16 when he became the first Chinese man ever to beat a top 20 player, dumping out Richard Gasquet.

His defeat of the Frenchman, ranked 14th, also meant Zhang was the first men’s player from China to reach the quarter-final of an ATP event since Pan Bing made the semi-finals in Seoul in 1995.

But matching Pan’s 17-year-old mark proved a step too far for the right-hander from Nanjing, with Mayer winning 6-3, 6-4.

Third seed Jo-Wilfried Tsonga, of France, defeated Russia’s Mikhail Youzhny 6-3, 6-2 to reach the semi-finals, where he will face Spain’s Feliciano Lopez, who beat American Sam Querrey 4-6, 6-4, 6-4.

In the women’s draw Li beat defending champion Agnieszka Radwanska 6-4, 6-2 to join Sharapova, Victoria Azarenka and Marion Bartoli in the semi-finals.

Victory for world number eight Li also secured her the final place at the end-of-season WTA Championships in Istanbul later this month.