Celtic supporters know better than most that the summer transfer window is rarely without its complications. While the focus often falls on new arrivals, contract renewals and major transfer pursuits, international football can quietly create selection headaches that only become clear once the domestic campaign is underway.
For clubs competing on multiple fronts, losing key players to international tournaments at crucial stages of the season is never ideal. Managers are often forced to reshuffle their plans, particularly when those absences coincide with high-profile fixtures that can shape the early momentum of a title challenge.
That balancing act is one Martin O’Neill has been navigating throughout the summer. With recruitment still ongoing and preparations continuing ahead of another demanding campaign, the Celtic boss is also keeping one eye on international commitments that could temporarily reduce his options.
One such issue has now been confirmed, with Celtic set to be without one of their attacking players for one of the biggest matches of the season.
Yang set to miss Rangers showdown

Celtic will be forced to cope without Yang when they face Rangers in the first derby of the campaign on September 20.
The South Korean winger has received a call-up for the Under-23 Asian Games, which run from September 19 until October 4.
Yang, 24, has been included as one of the overage players in the squad, with his participation earning him exemption from mandatory military service in South Korea.
The timing, however, means he will be unavailable for the opening Old Firm clash at Parkhead.
O’Neill addressed the situation by saying:
“He’s in, and also he’s got military duties and all that type of stuff, you know, so he’s got all of that there.
“So we might have to miss him for a number of weeks, but so be it. But we knew that before we extended his contract.”
Although Yang’s absence comes as a blow, Celtic were fully aware of the circumstances before agreeing to keep him at the club, meaning the situation has long been factored into their planning.
Celtic continue preparations
Elsewhere, O’Neill was satisfied with what he witnessed as Celtic opened their pre-season programme with a draw against Shelbourne in Dublin.
The experienced manager used two different starting line-ups across the two halves, allowing a number of academy prospects the opportunity to impress alongside senior members of the squad.
With further transfer business expected before the window closes, O’Neill continues to assess his options as Celtic prepare for another campaign where domestic success and European progress remain the club’s primary objectives.