Errani doing double duty at US Open

Women\'s doubles World No. 1 Sara Errani is bidding for a rare two-title run at the US Open, advancing to the women\'s doubles final Thursday after having booked a berth in the singles semi-finals. Italy\'s Errani and best friend Roberta Vinci defeated Nuria Llagostera Vives and Maria Jose Martinez Sanchez of Spain 6-3, 6-2 to reach a spot in Sunday\'s women\'s doubles final. Errani, a 10th seed in singles, also will play 14-time Grand Slam champion Serena Williams in Friday\'s women\'s singles semi-finals after defeating Vinci 6-2, 6-4 on Wednesday in an all-Italian quarter-final. Not since Williams in 1999 has a woman won US Open singles and doubles crowns, Williams beating Martina Hingis in the singles final and pairing with sister Venus to capture the doubles. Other women who have done the US Open singles-doubles twin wins in the Open era include Martina Navratilova, Arantxa Sanchez-Vicario, Billie Jean King and Margaret Court. Many times a player that goes deep in singles will quit in doubles but Errani sees one as helping the other. \"It\'s very good if you win the doubles. It\'s a good thing for your confidence,\" Errani said. \"It\'s a good day to practice for singles but also a good day to play doubles and have fun on the court.\" Errani, who became the first Italian woman in the Open era to reach the last four in New York, made her Grand Slam singles final debut last June at the French Open, losing to Maria Sharapova on the red clay of Roland Garros. Vinci and Errani have won seven doubles titles in 2012, including the French Open crown. Vinci ranks second in the world in doubles, but not in Errani\'s eyes. \"We\'re happy to be No. 1. It\'s a dream for us,\" Errani said. \"We are No. 1 together. It\'s not me No. 1 and her second.\" Vinci has seen Errani\'s game change over the past few years since she turned pro at age 20 in 2008. \"She\'s a little bit different. She\'s mature. She\'s more sure of herself,\" Vinci said. \"On the court, she is unbelievable.\" Errani credits older Italian women\'s players like Francesca Schiavone and Vinci with helping her develop into a stronger player. \"They had me start when I was little on the WTA, learn how to practice, how to do the right things,\" Errani said. \"I saw them and I wanted to make things similar to them.\" Errani will make at least $475,000 in singles alone from the Flushing Meadows fortnight and a singles crown would pay $1.9 million. But unlike at the French Open, she has not even thought about how she might spend it. \"At Paris I was looking much more,\" she said. \"This time, more relaxed. I haven\'t thought about it yet.\"