India's Leander Paes and Radek Stepanek of the Czech Republic reached the US Open men's doubles final on Thursday when Marc Lopez, playing with Spanish Davis Cup teammate Marc Granollers, retired.
Fifth-seeded Paes and Stepanek, the Australian Open champions, were level at 6-6 in the first set when Lopez called it a day after needing treatment on his left calf.
They will face either second-seeded Americans Bob and Mike Bryan -- the champions in 2005, 2008 and 2010 -- or the Paikstan-Dutch pairing of Aisam-Ul-Haq Qureshi and Jean-Julien Rojer in Friday's final.
"I feel sorry for Marc. We all come here to entertain you and they are great guys," said Paes.
"I have a great partner. He really pushed me today and pulled the whip out, which is probably what I needed. We are looking forward to the final."
Lopez's injury will be a worry for Spain ahead of their Davis Cup semi-final against the United States in Gijon from September 14-16.
The champions have already lost top singles player Rafael Nadal, who will miss the tie with a knee injury.