Dubai (dpa) - Roger Federer gave the thumbs-up Friday to a plan to team at the summer Rio Olympics with fellow Swiss Martina Hingis, with the all-star pair officially down to play in mixed doubles.The world number three confirmed the longstanding rumour that he and the 35-year-old Hingis would combine, giving Switzerland multiple medal chances with players including French Open winner Stan Wawrinka, Timea Baczinsky and teenaged Belinda Bencic all expected to be in the Games mix.Federer, 34, called himself