Del Potro through to final as injured Nadal retires
Juan Martin del Potro reached the US Open final on Friday after defending champion and world number one Rafael Nadal quit their last-four clash with a knee injury.
Third seed Del Potro, the champion in 2009, was 7-6 (7/3), 6-2 ahead when Nadal retired.
The Argentine will face either Novak Djokovic, the 2011 and 2015 winner or Japan's Kei Nishikori in Sunday's final.
Nadal, bidding for a fourth title in New York and 18th major, had spent the best part of 16 hours getting to the semi-finals.
That effort took its toll with the Spaniard twice needing to have his right knee bandaged before calling it a day after the conclusion of the second set.
