Serena Williams' hopes of a calendar Grand Slam in tennis are over.

The American lost her semi-final at the US Open to unseeded Roberta Vinci who will now play Flavia Pennetta in an all-Italy final.

Williams had been heavily tipped to complete the Serena Slam (winning all four majors within a calendar years) and appeared to be achieving just that after winning the first set 6-2.

But Vinci (32), who is ranked at No 43 in the world and had never advanced beyond a Grand Slam quarter-final, dug deep to win the second set 6-4.

She then repeated the feat in the final set to take that 6-4 and pull off a momentous - and in the circumstances - historic victory.