Matt O'Riley is leaving. Reo Hatate is Leicester-bound. Cameron Carter-Vickers is en route to Atalanta. Oh, and now Manchester City are keen to swipe Kyogo Furuhashi.

A week is a long time in football, so they say. But for Celtic supporters with an eye on the latest speculative transfer rumblings, the last seven days may have felt like a life sentence.

That's the downside of having a team firing on all cylinders, one could posit, whereby a fine vein of preseason form has segued rather effortlessly into the domestic campaign.

Indeed, Celtic look like a force to be reckoned with ahead of their first showdown of the season with Rangers next Sunday – but there is a tangible sense of unease every time Fabrizio Romano hits send on his latest doom-bringing, rumour-stirring social media post that involves the reigning Scottish champions. Disclaimer: other brands of trigger-happy online transfer guru are available.

Callum McGregor has seen it all before, though. Sure, the twilight stretch of any transfer window can be precarious as the big-money clubs circle like vultures in search of last-gasp bargains, but the chiselled Celtic captain's focus remains squarely on the task(s) at hand: training hard, playing well, ignoring the noise; rinse and repeat.

"The football has been excellent so far," McGregor said ahead of tomorrow's Scottish Premiership trip to St Mirren. "The challenge now, though, is to stay on top of that. Obviously the football's good, everybody's working hard, training hard, playing for the team. The only thing is complacency – we just need to guard against that and try and keep the performance levels as high as we can for as long as we can.

"We try to keep as many good players in the building as possible. We're a week away now from the window shutting so hopefully we can get through that with minimal disruption and upheaval. Then we can continue to focus on the football."

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On the pitch, that's always been the 31-year-old's job, ever since breaking into the Celtic first-team under Ronny Deila 10 full years ago as a fledgling attacking midfielder. Now, three years' deep into the Parkhead side's captaincy and a big part of maintaining that focus involves matters off it.

"I think we just try and normalise [the noise] as much as possible," McGregor added. "We all know it's a potentially sticky period twice a season where people can feel unsettled. So the best thing for the players is just treat it as normal. It's another working day. We come in, we try to train as hard as we can, we try to get better and improve the team.

"The more you talk about it then it becomes a bigger thing. It's actually the less said, the better. We train together, we use all the energy and anxiety, and just put that straight into the training and hopefully the levels go up.

"My job doesn't change too much in that process, I'm always trying to set the tone and set the level for the players and that's not really any different in these last few weeks as it is any other time."

McGregor freely acknowledges the inevitability of squad turnover during this period of the season, and he more the welcomes the idea of new faces entering the squad as opposed to heading in the opposite direction.

So far this window, Brendan Rodgers has signed Viljami Sinisalo, Kasper Schmeichel, Paulo Bernardo and Adam Idah – the latter two of which have committed the next five years of their careers to Glasgow's east end following successful loan spells last season.

Time is, of course, marching on towards the end of the current transfer window – the Scottish window shuts at 11pm on Friday, August 30 – but the manager again spoke candidly about his abiding desire to add quality to the current squad in his pre-match press conference ahead of Sunday's match.

From here, Celtic prepare for a typically busy fixture schedule between now and the next international break.

To this end, McGregor added: "That's modern day football for you. This is what we try to normalise at the club. Big weeks – you have to come through them, you have to get results, you have to conduct yourself in a certain manner.

"And once it all washes away, then the main focus is football and that's why we're here. Everything else, all the noise, that will all be external. For us, we train as hard as we can, then when we get a chance to play, we give the maximum try and get three points and move onto the next one."

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The next one after St Mirren, of course, is Rangers. At Celtic Park. With another 100 percent fan deficit in Celtic's favour.

What lies ahead remains to be seen, and nothing in football is ever certain. But McGregor and his peers will enter next week's showdown as firm favourites.

"For sure, you have to win every game when you are here [otherwise] it's crisis mode again," McGregor added. "That's life at Celtic, everyday you're under pressure to perform every game. You have to win. If you don't, then it's a crisis again.

"We know how important that is, and the group understands that. The way they've started the season has been amazing, but now we go full focus on tomorrow, and then the following week as well.

"Everything's a lot slicker on the pitch at the moment. Everybody's been together now for a year, and the guys that came in in January are now up to speed as well, which is good. You can see the team are really understanding what it is we're asking them to do and how to execute it.

"Like I said, everybody's playing for the team, they all know their job and they're giving the absolute maximum to that. Yeah, there's probably a big difference from where we were 12 months ago, but the good thing is I think we can get even better as well."