American supermodel Gigi Hadid has revealed she injured her arm while training with tennis star Serena Williams for a virtual charity tennis tournament. The Stay at Home Slam is set to be streamed on Facebook Gaming and on the tennis Facebook page of IMG on Sunday. While taking tips from Serena ahead of the online celebrity match, Gigi, who is expecting her first child with singer boyfriend Zayn Malik, said she pulled her entire arm the first time she practised on swing mode.