Rangers defender Leon King had to be substituted just 13 minutes against Union Saint-Gilloise.
The 21-year-old started at full-back in the Europa League tie with James Tavernier moving into central defence for the final league phase match.
However, King was forced off after struggling with his vision.
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The defender had taken a knock to his head after an aerial duel in the first minute of the match.
King bravely played on but was clearly feeling the affects of a head knock as he signalled he could not continue.
After a crucial challenge inside his own box, King sat on the turf and signalled to the bench with complaints over his vision.
King was checked by Rangers medical staff before being ushered off the pitch as he was replaced by Ross McCausland.
