It remains to be seen if Sexton will be fit enough to face New Zealand this weekend and Schimdt is worried by the lack of caps his reserve fly-halves Paddy Jackson and Ian Madigan have between them.
"I guess we'll find out the degree of his injury and then that will either make a decision easy for us, because it looks good or it doesn't look good," said Schmidt.
"If it's halfway in between, then certainly my expectation would be that he would have to train on Friday.
"He hasn't really spent that much time with us training, he had a little hip-flexor issue plus we left him to rest against Samoa just because of the attritional game time he had already accumulated.
"And I think the wear and tear of that game time has consequences, and unfortunately those consequences have fallen in our lap.
"Paddy Jackson and Ian Madigan have a handful [of caps] each. That's a very big gap in terms of learning, experience and opportunity to maybe make some errors and learn from them. And they will be surrounded by some experienced players.
"So it's important for us to try to get the right players around the ten if it's not Jonny."