Ferris limped out of training in Durban today with a sore knee today and joined Cardiff Blues wing Leigh Halfpenny in going to hospital for tests.
The man who has scored two sensational breakaway tries for the Lions to date on tour was forced to pull out of the replacements for the opening game because of a slight calf strain.
The Lions management sent him to hospital with Halfpenny as a precaution after training in Durban. Halfpenny, who aggravated his old thigh muscle problem, has been removed from the replacements bench for Wednesday night's game against The Sharks, but Ferris was not involved.
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