"Liam's injury is worse than we feared," Robins boss Gary Johnson told the Bristol Evening Post.
"He went for the scan on Monday and it showed up ligament damage. He will be out for a minimum of three weeks and maybe longer."
Former Manchester United manager Sir Alex Ferguson was in the crowd for the Europa League final between Dnipro Dnipropetrovsk and Sevilla.
LEADING scorer in League One; a Wembley winner and now crowned the PFA Fans Player of the Year - its
It has been a dream end to an incredible season for Harry Arter and Bournemouth as they prepare for life
The 32-year-old Brazilian right-back has spoken out about his contract situation and what he perceives to be a lack of
On Wednesday, the US Department of Justice indicted nine Fifa officials for racketeering, conspiracy and corruption.
Chelsea won the Premier League with three games to spare, while Hull, Burnley and QPR were relegated into the Championship.