Smith has been in imperious form for the GUINNESS PRO12 leaders, with six starts in the front row already this term.
And the 20-year-old's absence was felt as the Welsh region surrendered their 100 per cent record at Ulster on Friday night.
However he may be missing from PRO12 action for a little longer, after Gatland revealed Smith suffered a chest injury in Wales' 34-16 defeat to world champions New Zealand in Cardiff on Saturday and admitted there are general fitness concerns regarding his whole squad.
"Nicky Smith did a pectoral muscle," Gatland confirmed.
"Where they're [southern hemisphere sides] used to playing at that intensity all the time, right at the very edge, sometimes our players are coming to us not quite with the same numbers.
"We've got to replicate that at training, just to get them up to the level that they're going to expect to face against the southern hemisphere teams."
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