Lausanne, Switzerland (dpa) - Roger Federer and Martina Hingis are preparing to reform a partnership from 15 years ago to enter the mixed doubles of the 2016 Olympic Games, a report said Sunday.Federer, 34, and Hingis, one year his senior, won the Hopman Cup mixed team event in Perth, Australia, in 2000 but could now go for gold in Rio, Le Matin newspaper reported.According to the paper, Federer has agreed to partner Hingis at the Games after she first floated the idea in 2014.