Martin O'Neill admitted he is trying to sign cover for Kieran Tierney in the left-back position, while giving his thoughts on the Celtic debuts of Camilo Duran and Kasper Hogh.
On flag day, the champions beat Dundee in their Premiership opener but it was not a vintage performance as they edged a narrow one-goal win.
Tierney was one of the standout performers following transfer links to La Liga side Osasuna, while the club's two summer arrivals to date, Duran and Hogh, were handed starts on their debut.
It is clear the Parkhead side need more depth, while reinforcements will be needed should the likes of Arne Engels and Alistair Johnston move on. O'Neill admits left-back is a position he is looking to add in, to provide Tierney with support.
Last season's loanee Marcelo Saracchi was a target but looks set to move to MLS with Houston Dynamo.
The 74-year-old told BBC Radio Scotland: "Of course, and that's something we are definitely looking at. Kieran, with the best will in the world, will not get through every single game.
"If we are going to be playing in European football one way or the other, it would be a bit like last year; he was recovering then and didn't see some games out because he puts so much into it. That's dead right. So we're looking along those lines.
"We've got some young lads in the academy who are very fine players, but I think it's a wee bit early for them."
Hogh, playing at centre-forward after his £11 million move from Bodo/Glimt, missed a number of gilt-edged chances while Duran played outside him on the right.
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O'Neill backed the Dane to come good once he is able to train with his teammates more, after only arriving last week.
He said: "Kasper had a number of chances; he could have scored two or three goals quite easily. I think it was one of those evenings where you want to try and impress, and of course he wants to impress the home fans here.
"It's the first time he's played for us, he’s done some training, and he will definitely get better. There's no question about it, and he will score goals for the football club.
"For Duran, he played a little bit out of position because we haven't actually had time for them to play together yet. Hopefully in the next couple of weeks, we'll be able to work on that in training. He can turn people as he did on the edge of the six-yard box, brilliantly really, and crosses the ball that we could have scored from. That's his game; that's what he can do. From the wide right-hand side, I think sometimes the game might pass him by.
"Overall, again, it's the first time the two of them have played together. I'm not even sure that we did that many training sessions with the two of them playing together, but it's great. Those are two really fine players and I think that they will help us."
