Liverpool midfielder Naby Keita was taken to hospital after sustaining a suspected back injury during his team's 1-0 defeat by Napoli in the Champions League on Wednesday, the Premier League club said. The Guinean was taken off the pitch on a stretcher midway through the first half of the group stage tie in Naples and is a major doubt for Liverpool's top-of-the-table Premier League clash at home to Manchester City on Sunday. "Keita was transferred to a local hospital with the club doctor, where -- with the midfielder's agreement -- he underwent a number of precautionary health checks to assess his condition," Liverpool said in a statement. Lorenzo Insigne scored in the 90th minute to send Napoli top of Group C on four points, one ahead of Liverpool and Paris St Germain. Red Star Belgrade are bottom with one point. (For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)