Del Potro, Tsonga march into Shanghai semi-finals

Juan Martin del Potro kept his errors to a minimum as the Argentine breezed past Spain`s Nicolas Almagro 6-3 6-3 to march into the semi-finals of the Shanghai Open on Friday.

Del Potro, seeded sixth, had also defeated Almagro in last week`s Japan Open semi-finals and now needs one more victory to seal his spot for the season-ending ATP World Tour Finals in London next month.

The Argentine, who was suffering from fever during the earlier stages of the hard-court tournament, committed just eight unforced errors during his win and faced a single break point, which he went on the save.

"I played very well today, very solid," del Potro told reporters. "I played aggressive. I hit my forehand very well.

"I like the way I played today. I just want to keep improving (and) keep going far in this tournament."

Frenchman Jo-Wilfried Tsonga also took a positive step towards confirming his spot for London with a comfortable 6-2 6-3 win against German Florian Mayer on Friday.

World number three Andy Murray`s withdrawal from the Tour Finals due to injury has meant anyone finishing ninth or better in the race to London will qualify for the prestigious season-ending tournament.

Top seed Novak Djokovic, who lost his world number one ranking to Rafa Nadal on Monday, will take on France`s Gael Monfils for a place in the last four.

Spain`s Nadal, who last week lost to Djokovic in the China Open final, faces Swiss Stanislas Wawrinka in the other last-eight clash on Friday.