* Defending champion Djokovic could face Ferrer in semis
* Serena Williams to face fellow American Coco Vandeweghe (Adds quotes and details)
Andy Murray's hopes for a maiden grand slam at the U.S. Open may require him to beat world number one Roger Federer for a second time in five weeks after the duo were placed in the same half of the draw on Thursday.
Top seed Federer beat Murray last month to win his seventh Wimbledon crown and record 17th grand slam title but the Briton gained revenge when he crushed the Swiss master in the final of the Olympics at the All England Club on Aug. 5.
Five-times U.S. Open champion Federer plays American Donald Young in the first round of the Aug. 27-Sept. 9 tournament in New York, while third seed Murray faces Alex Bogomolov Jr. of Russia.
Defending champion Novak Djokovic, who kicked off his North American hard court season with a win in Toronto before falling to Federer in the Cincinnati final, opens against Italy's Paolo Lorenzi and could face fourth seed David Ferrer of Spain in the semi-finals.
"Obviously I have great memories of the U.S. Open from last year," said second seed Djokovic, who entered the 2011 U.S. Open having suffered just two defeats all year.
"In 2011 it was a remarkable seven months of my career, that I crowned when I won another grand slam title, with my first U.S. Open. I am really happy to be back."
World number three Rafa Nadal, who has not competed since suffering a shock second-round Wimbledon defeat, withdrew from the U.S. Open last week with a nagging knee problem.
In the women's event, tournament favourite Serena Williams avoided most of her rivals as she was placed in the bottom half of the draw alongside second seed Agnieszka Radwanska.
The American fourth seed, who turns 31 next month and is coming off Wimbledon and Olympic triumphs, begins her title campaign against compatriot Coco Vandeweghe.
Defending women's champion Samantha Stosur of Australia, who beat Williams here last year for her first grand slam title, is in the top half together with world number one Victoria Azarenka and third seed Maria Sharapova.
"Winning here last year was an absolute dream come true. It's been a bit of an up and down year but I have been feeling good these past few weeks," said Stosur. "This is a tournament and a surface that I think suits my game, so hopefully I can have another great two weeks."
Women's top seed Azarenka, who won her first grand slam title at the Australian Open in January, opens against Alexandra Panova of Russia while Wimbledon runner-up Radwanska plays Russian Nina Bratchikova.