BEIJING (AFP) - Tennis world No. 2 Rafael Nadal staged an extraordinary comeback in his China Open quarter-final match Friday, keeping alive his hopes of unseating Novak Djokovic at the top of the men's rankings.

The Spanish number two seed in Beijing looked to be heading for a crushing defeat after Fabio Fognini claimed the first set and powered to a 4-1 lead in the second.

But Nadal broke the Italian's serve in the seventh game, before winning the next three to take the second set 6-4.

Fognini, who is ranked 19th in the world, won the opener of the third set, but Nadal sealed his passage through to the semi-finals with victory in the remaining games.

Nadal is aiming to unseat Djokovic at the top of the men's rankings by making the final in Beijing.

Current China Open champion Djokovic can only remain top if he reclaims his title and if Nadal fails to win his semi-final against either American John Isner or Czech fourth seed Tomas Berdych.

Nadal has not lost a hardcourt match all season.

The China Open reaches its climax on Sunday.