Best insisted that Porter can cope on his Test match baptism of fire however, despite the 22-year-old only switching from loosehead to tighthead midway through last season.
But hooker Best revealed Sexton did take part in the session later on, easing any concerns he could join Tadhg Furlong, Iain Henderson and Robbie Henshaw on the sidelines.
Schmidt has named Connacht's Quinn Roux on the bench, alongside Jack McGrath, Seán Cronin, John Ryan, Jack Conan, Kieran Marmion, Joey Carbery and Fergus McFadden.
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"Are we going to be able to test this Welsh defence, that is incredibly well drilled by Sean Edwards, who is a very shrewd, experienced operators in both codes (union and league), and he'll have come up with a plan he believes will stop Ireland?".
Porter showed his mettle against Italy when Furlong limped off after only three minutes. I know it is not the same level and Rob Evans [the Wales loose-head] is a tricky customer with his angles and stepping around, but they have got to learn somewhere.
Asked later whether such questions annoyed or frustrated him when his side was creating the opportunities he suggested, Schmidt replied: "I am not even saying there is all this opportunity". Munster's Chris Farrell, 24, makes his championship debut in place of Henshaw.
Gatland has already said that his team will be looking to put pressure on both Ireland half-backs by closing down their space to limit the effectiveness of their kicking game. "Chris has been a long-term project and he did well against Argentina in November". Away wins have been precious in this competition and the victory in Paris got them off to the ideal start which was backed up by their 56-19 win at home to Italy.
Cian Healy, who returns to the pack alongside CJ Stander in the only other change, was excited about the impact the younger players could make up front.
The New Zealander took on the head coach role in December 2007, and made an immediate impact by leading Wales to a Six Nations Grand Slam during his first year in charge in 2008.
"Matches against Wales tend to be close", Schmidt said. "It's all about the fine margins". Wales will vary their game, driving mauls, putting the ball in the air a lot and playing with width.
"Hopefully he can get a win in his 101st test which would be great", he dryly observed.
Gatland felt hard done by when he was not kept on as Ireland coach with his Irish assistant Eddie O'Sullivan replacing him in 2001 after three years in the role.
"Last year we lost a couple of those through our own doing and also good play by Wales".
"And if you can get that it keeps the players interested, and if you can keep the players interested you can stay around, because you get performances and success".