Leander Paes and Martin Damm of the Czech Republic upset Mark Knowles of Bahamas and Daniel Nestor of Canada to advance to the semi-finals of the Cincinnati Masters in Ohio.

The seventh seeded Indo-Czech pair pulled off a 3-6, 7-5, 10-4 win against their third opponents in the 93-minute affair on Friday.

The Indo-Czech pair, winner of the ATP event in 's-Hertogenbosch, the Netherlands and runner-up at the Australian Open, broke Knowles-Nestor twice to save four points in the quarter-final match of the Tier-I event.

Paes-Damm will take on defending champions and second seeds Jonas Bjorkman and Max Mirnyi in the last four. Their last meeting in the quarter-finals of the Rogers Cup in Toronto last week was won by Paes and Damm.