The Saracens loose-forward was concussed nine minutes into Wednesday’s 17-16 Pool C defeat by Georgia which earned a first World Cup point for Namibia but not a first win.
Burger will not be available for their final match against Argentina in Leicester on Sunday and having already announced his retirement after the tournament in England, he has played his last match for his country.
“It was a huge disappointment that I could not complete last night’s match and an even bigger disappointment that I will not be able to play on Sunday,” Burger said in a Namibia Rugby Union statement on Thursday.
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“I am very proud of my team and it’s not the way that you would want to end an international career. But that’s the game of rugby for you.”
Burger’s test career spanned nine years and 36 caps, including three World Cups in 2007, 2011 and 2015.
He equalled former hooker Hugo Horn’s Namibia record of 11 World Cup appearances.
(Reporting by Nick Said, Editing by Ed Osmond)
