World number two Rafa Nadal sailed into the quarter-finals of the China Open, his first tournament in 13 weeks, with a 6-3, 6-4 win over German qualifier Peter Gojowczyk.

The Spaniard, returning from a wrist injury, won 85 per cent of his first service points against the German and took an hour and 45 minutes to seal victory and set up a last-eight clash with Martin Klizan at the ATP 500 event.

Slovak Klizan was leading 6-2, 3-0 when seventh-seed Ernests Gulbis retired due to a right shoulder injury.

Third seed Tomas Berdych moved up a place to seventh in the race to the season-ending ATP World Tour Finals in London after his 6-3, 6-4 victory against wild card Viktor Troicki despite a poor serving display.

Elsewhere on Beijing's blue hard courts, Bulgarian Grigor Dimitrov beat Spaniard Pablo Andujar 6-4, 6-4 to set up a quarter-final clash with world number one Novak Djokovic, while sixth-seed Andy Murray beat Pablo Cuevas 6-2, 6-2.

Exits for Kerber, Venus

In the women section, Russian Svetlana Kuznetsova upset seventh-seed Angelique Kerber in three sets, while Petra Kvitova also reached the quarter-finals without hitting a ball after American Venus Williams withdrew with a viral illness.

Twice champion Kuznetsova dropped the first set but eventually prevailed 2-6, 6-4, 6-3 in the two-hour-and-eight minute battle that complicates her German opponent's hopes of qualifying for the season-ending WTA Finals in Singapore.

Kerber is ninth in the race for next month's event featuring the top eight players and could have improved her position with a better showing in China.

Second seed Simona Halep, one of the four players to have already secured a place in the Singapore event, battled past Andrea Petkovic of Germany with tie-breaks separating the pair in two of the three low quality sets.

The Romanian, who produced 91 errors, fought for more than two and half hours to tame Petkovic 7-6, 5-7, 7-6 and reach the last eight where she will meet Ana Ivanovic, who downed Sabine Lisicki 6-3, 7-5.

Source: Reuters