World number ones and title holders Novak Djokovic and Naomi Osaka have been named the top seeds for the US Open which starts on Monday in New York. Three-times US Open champion Djokovic, who comes into the tournament having won his fifth Wimbledon title, is followed in the seedings by 2017 winner Rafael Nadal. Roger Federer will begin his quest for a 21st Grand Slam crown as the third seed. He is followed by Austrian Dominic Thiem, Russia's Daniil Medvedev and Germany's Alexander Zverev. Former champions in the list of 32 men's seeds also include Marin Cilic (2014) of Croatia who is 22nd and Stan Wawrinka (2016) of Switzerland who is 23rd. French Open winner Ash Barty is seeded second behind Japan's Osaka, followed by Czech Karolina Pliskova and Wimbledon champion Simona Halep. American Serena Williams, last year's finalist who is seeking a record-equaling 24th Grand Slam title, is seeded eighth while another former winner, Sloane Stephens, is 11th. Angelique Kerber, the 2016 champion, is seeded 14th. — Reuters