"Unfortunately, Gethin's calf is still not 100 per cent," said Gatland
"We have had him rescanned, and there is some damage in the calf.
"I would say it probably rules him out of contention for the South Africa game if selected (for the squad).
"He is as frustrated as anyone. He has worked really hard, he just hasn't been able to get himself right.
"We know what a quality player he is, and the hope is he will show signs of improvement and maybe we will be able to consider him for other games in the World Cup."