The French kicker suffered a dead leg in the 19-12 quarter-final win over England last weekend.
"He kicked after being injured and that aggravated his injury and that is why he has been relaxing," said Quesada.
"He has been recovering properly and his best training this week has been to recover, to look after his leg.
"We will wait until then last minute before we decide whether he will be kicking or not."
If Yachvili fails to recover in time for the Wales match, Morgan Parra is likely to take over kicking duties.