• Former world No1 plays top-level tennis for first time in eight years• Poland lead 1-0 after opening singles rubber in Zielona GoraMartina Hingis, five times a grand slam singles champion, made a courageously impressive return to top-level singles tennis in the Fed Cup but was eventually outplayed by Agnieszka Radwanska.Hingis was persuaded to play her first tour-level singles for nearly eight years because of injuries in the Switzerland team for the World Group play-off against Poland in Zielona Gora.