Argentina progress as Novak Djokovic retires

Serbia's Novak Djokovic was forced to retire from his Davis Cup semi-final tie against Argentina's Juan Martin del Potro with injury.

The world number one pulled out while trailing 6-7 0-3 to give Argentina an unassailable 3-1 victory.

"I feel very disappointed to end the tie in this way," said the US Open champion. "I tried although I was only 60% fit and I went into the match knowing there was a risk of aggravating the injury which I first felt at the US Open.

"We knew my condition was not good but we believed that even so I would have a better chance against Del Potro than my teammate Viktor Troicki would. At the end of the day it was my decision and it backfired."

Argentina will now face Spain in December's final.