Yuki Kobayashi Celtic first-look: What did we learn?

First half

Lining up at left centre-back next to Carl Starfelt, who moved over to replace the injured Cameron Carter-Vickers, Kobayashi cut a relaxed figure in the moments before his first green-lit huddle as the Celtic Song faded into crowd noise.

It took almost three full minutes before he got a touch, such was the attacking intent displayed by the champions from the very outset. That touch was a relatively straightforward pass out to Josip Juranovic at left-back.

"He's a left-sided centre-back, which for us was key to bringing him in. He's good on the ball and a good, strong defender" was Postecoglou's summation of his new man pre-match.

The ball-playing part was certainly in evidence, if subtly, early on when he chose to deliberately keep the ball in play near the left byline in the St Mirren half when perhaps letting it run out would've been the more prudent course.

He was happy to attempt line-breaking passes when possible - which is not always against an opposition like the Buddies - with Reo Hatate and Jota more often than not his intended recipients.

He lost his first aerial duel to Curtis Main, whose flick-on actually resulted in a foul against the Japanese and a free-kick for Saints in what became their first real foray into the home half eight minutes in.

Just after the 10-minute mark, neither Kobayashi nor Juranovic noticed Main slipping in behind them when the ball was knocked back into the Celtic six-yard box. The Englishman knocked the ball beyond Joe Hart but it served as a mere warning sign for the new man as it was chalked off for offside.

If Kobayashi was in any way shaken by almost conceding so early in his debut, he did not show it. His very first involvement thereafter was to play a head-up, unflustered ball to Hatate after inviting pressure from a St Mirren forward.

To cap his opening quarter-hour as a full-fledged Celtic player, he came up for a corner and struck the post with a semi-acrobatic volley after Trevor Carson had parried away a Starfelt shot.

Before the half was out he had displayed some of that defensive solidity his manager spoke of too when a loose Starfelt pass left him one-on-one with Jonah Ayunga.

Faced up straight on, Kobayashi seemed in total control of the situation by ushering the Kenyan one way and then the other without allowing himself to be spun around in the process and ultimately blocked the attempted shot.

His first half as a Celt closed with Kobayashi having completed the most passes of any player in the match - something he will find is a regular feature of his working days when playing in green and white in Scotland.

Second half

With Kyogo Furuhashi scoring his second, and Celtic's third, so early in the second half the nature of the match naturally changed and Kobayashi's night became even less about preventing a St Mirren upset and almost totally about keeping his and the team's intensity up as high as possible.

Most of the time that meant ensuring he got the ball out of his feet and onwards as quickly as he would if it were 0-0 and - to his credit - that attitude did seem to be his go-to.

That said, Main has been a handful for more physical centre-backs than Kobayashi and if there is a side of his first outing to highlight critically it is surely his relatively poor performance aerially.

Indeed he was just two from five at the break and by the end of the match had failed to enhance his output in that regard, ending with two from eight.

Overall, plenty has been made of the difference having a true lefty next to Carter-Vickers in the heart of the defence could make to Celtic's play.

Three things about that: 1) much of that chat is centred round competing better at Champions League level, which St Mirren at home is decidedly not; 2) right-footed Juranovic being chosen at left-back rather than one of the natural left-backs somewhat negates the theory behind a left-footer's impact at centre-back;  3) added to that it was, of course, not Carter-Vickers he partnered in this one and so a true insight into the possible pairing of the future was not on the menu.

But you have to start somewhere and, as starts go, Kobayashi's was about as good as he or his manager could have hoped for.