Novak Djokovic’s hopes of finishing the year ranked world No.1 have suffered a blow with a quarter-final defeat by Stefanos Tsitsipas at the Shanghai Masters.

The young Greek has struggled in recent months after his stellar start to the season but has been superb in a 3-6 7-5 6-3 victory in just over two hours, claiming a second career win over Djokovic.

Tsitsipas will face third-seeded Russian Daniil Medvedev in the last four.

Djokovic tops the rankings but trails Rafael Nadal in the yearly standings and, with the Spaniard absent, had hoped to make up significant ground.

In the first Shanghai quarter-final, Medvedev accounted for 10th-seeded Italian Fabio Fognini, 6-3 7-6 (7-4).

Tsitsipas’ win ensures he will debut at next month’s elite season-ending ATP Finals in London.

AAP