Third seeds Leander Paes and Radek Stepanek qualified for the semi-finals of the Barclays ATP World Tour Finals after winning their second Group A match against sixth seeded Spanish duo of Marcel Granollers and Marc Lopez in straight sets here on Thursday.
The Indo-Czech pair got the better of Granollers and Lopez 7-5 6-4 in an hour and 32 minutes.
Paes and Stepanek, who had also won their first group match against Aisam-ul-haq Qureshi and Jean-Julien Roger, Thursday lost just five service points in the first set that lasted 46 minutes.
They created one set point opportunity on Lopez's serve in the 12th game after Paes hit a forehand down the line, which Granollers volleyed into the net. Stepanek was aggressive on a backhand return and targetted Granollers, who was on the defensive, and could only hit long.
The Spaniards, however, regrouped to earn three break point chances in the first game of the second set out of which they converted one.
A four-time runner-up in this event with two different partners, Paes then managed to steady the ship by drawing on all his experience.
The Indo-Czech duo gained parity in the set by breaking Lopez. But their celebrations were short-lived as Stepanek lost his serve, volleying into the net at 30-40, for a third successive service break, even as Granollers took a 4-2 lead.
Momentum in the set continued to swing back and forth as Lopez was again broken for 4-4.
Paes, making his 14th appearance at the season-ending championships, and Stepanek then grew in confidence and at 5-2 broke Granollers for the match and a place in the last four stage of the championship.
They won 28 of their 35 service points. Granollers and Lopez, on the other hand, could win only 11 of their 25 service points.
The Paes-Stepanek pair had won this year's Australian Open, Sony Open Tennis and Shanghai Rolex Masters.
Paes and Stepanek, who now have a dead rubber in their final match against top seeds Bob Bryan and Mike Bryan, are making their first maiden together at the Tour Finals.