South Africa and Sharks forward Eben Etzebeth has suffered a return of concussion symptoms and been sent to specialists, ruling him out of action for the immediate future.
The lock forward is a two-time World Cup winner with the Springboks and his performances last year saw him nominated for World Rugby's Player of the Year for a second successive time.
Etzebeth has not played since suffering concussion in the Sharks' 39-21 home win over the Exeter Chiefs in the European Champions Cup on 7 December, however.
The Sharks said Etzebeth had "suffered a return-of-symptoms of his recent concussion".
"The Sharks take this injury very seriously and player welfare remains our top priority. Eben is being managed by concussion specialists. He will be cleared to return once they are fully satisfied that his injury has completely resolved."
The 33-year-old has previously struggled with concussion symptoms that also kept him on the sidelines at times.
When he played at Toulon in France in 2021 he spent three months out after suffering three concussions in the season.
He was also out with concussion after being hurt playing for South Africa against England at Twickenham in 2016 and again in Super Rugby action in 2019.
The Sharks are due to play Leinster and Ulster in the latter stages of the BKT United Rugby Championship.
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