Serena outlasts Venus

Fourth seed Serena Williams edged a tightly contested quarter-final clash with sister Venus 7-6 (8-6) 7-6 (9-7) to book a place in the last four of the US Open.

Serena trailed 5-3 in both sets and faced set points on both occasions but she battled back to secure a place in the semi-finals at the tournament for the first time in six years.

The 26-year-old triumphed here in 1999 and 2002 and if she repeats that success this year she will become the world number one for the first time since a 57-week reign from 2002-03.

Serena has won three titles and reached the quarter-finals or better in 10 of 11 events played but remains without a Grand Slam title since the 2007 Australian Open.

She will play Dinara Safina in the semi-final after the Russian had earlier defeated Flavia Pennetta 6-2 6-3.