Gloucester's James Forrester looks set to miss the World Cup later this year after rupturing a cruciate ligament.
Forrester's injury is a setback to England's World Cup preparations
The England number eight suffered the injury to his right knee in Saturday's 35-13 win over Bristol.
"It's devastating news for Jamie and Gloucester, particularly at this stage of the season," said coach Dean Ryan.
"It's also likely he will miss out on a World Cup place. We all wish James the very best in his recovery and we are right behind him."
Forrester was set to be named in England's 32-man squad this week for the two-Test tour to South Africa this summer.
The 26-year-old , who signed a new deal that will keep at Kingsholm until 2010 in January, sees a specialist later this week and is likely to require an operation.