CELTIC, like most modern football clubs, have a multi-cultural squad.

This cosmopolitan outlook means every international break sparks an exodus from Lennoxtown as most of the first-team join up with their countries across the globe.

While European nations will not be in action again until March, Celtic still have plenty to ponder with upcoming World Cup qualifying ties elsewhere.

Chief among fans' concerns is the possible absence of Kyogo Furuhashi and new Japanese signings like Reo Hatate and Daizen Maeda while Australia will likely call upon Tom Rogic in the same timeframe.

What players might be forced to miss crucial club games? When will they return and are there any additional obstacles when they do? 

Here's everything you need to know and some (hopefully) handy graphics to help you remember...

African Cup of Nations

Celtic players affected: None

Let's start with this as it is now in full swing at the time of writing.

There is no Celtic involvement in this year's AFCON although three former players - Kundai Benyu, Mubarak Wakaso and Saidy Janko - are there with Zimbabwe, Ghana and Gambia respectively. Ismaila Soro has been capped by the Ivory Coast but was not called up.

READ MORE: How Kyogo Furuhashi became Scottish football's leading man in less than six months

The tournament could, however, impact the Hoops' upcoming opponents. Alloa Athletic, who they visit in the Scottish Cup on January 22, could be without defender Fernandy Mendy if Guineau-Bissau make it out of the group stages. 

In the same section, Nigeria's progress will determine whether Rangers are without Joe Aribo for the Glasgow derby on February 2. The Super Eagles would need to make the semi-finals for the midfielder to be rendered unavailable.

Japan's World Cup qualifiers

Almost certainly affected: Kyogo Furuhashi. Potentially affected: Daizen Maeda, Reo Hatate. Unlikely to be affected: Yosuke Ideguchi.

The big one, really. Japan's fixture list has been altered recently with their Kirin Cup (remember that?!) match against Uzbekistan cancelled due to growing Covid rates and additional restrictions being placed on entry into the country.

Both Maeda and Hatate were named in the squad for that game, which was scheduled for January 21. It should be noted it was made up of J1 League-based players, so it is unclear if they would have been withdrawn as a result of joining Celtic. In any case, it is no longer a concern.

Japan's focus is on a crucial qualifying double-header against China PR on January 27 and Saudi Arabia on February 1. The Blue Samurai, currently second, are aiming for a top-two finish in their group to avoid the play-offs.

Both matches are in Saitama and are currently slated to go ahead despite border control restricting 'new entries' by foreign nationals until at least February. Opponents will need special dispensation and visas but Japanese nationals are allowed so there should be little issue for any Celts called up in terms of getting there and back (except for the 11,500-mile round trip, that is).

Celtic Way:

This will certainly affect international regular Kyogo - the striker played in 11 of Japan's 12 matches last year - but may not rob Ange Postecoglou of Maeda or Hatate.

Maeda has been capped but has not played since the Copa America in June 2019 while Hatate remains uncapped at senior level. Both were called into the wider squad for the November qualifiers though neither were handed a matchday strip, so it is unclear whether head coach Hajime Moriyasu will include them this time round. Yosuke Ideguchi has also been capped but has neither played nor been in a squad since December 2019.

In practice, Japan's fixtures will mean Kyogo misses the matches against Hearts (a) on January 26, Dundee United (h) on January 29 and Rangers (h) on February 2, with Maeda and Hatate's availability dependant on their inclusion.

For those keeping an eye on Google news for squad announcements, the JFA have announced two of the last three squads exactly one week before the first game of the schedule with the other announced 10 days prior. That puts a reasonable estimate for this one around January 17 to January 20.

Celtic Way:

Australia's World Cup qualifiers

Almost certainly affected: Tom Rogic.

Spare a thought for the midfield magician and hope he's in a frequent flyer programme.

Australia, currently third in the same group as Japan with the same top-two aspirations, are down to play games in Melbourne (against Vietnam on January 27) and Muscat (against Oman on February 1). That's over 21,000 miles Rogic will have to travel, not even counting the fact he'll have to do it the Neal Page/Del Griffith way rather than as the crow flies.

Given the importance of these two matches to the Socceroos' World Cup hopes, there is almost no chance Rogic is left out.

Celtic Way: Australia are currently third in their qualifying section with games against Vietnam and Oman loomingAustralia are currently third in their qualifying section with games against Vietnam and Oman looming

The 29-year-old has over 50 caps for his country and although he missed their first four matches last year he had returned to play an instrumental role in four games on the spin before a hamstring injury forced him to miss the final two of 2021.

These matches are also still slated to go ahead as planned, despite Australia topping one million 'active Covid cases'. Entry, even for elite athletes, is generally subject to full vaccination or a medical exemption (the latter propelled into the public eye by Novak Djokovic in recent days).

Like with Kyogo, in practice these commitments will mean Rogic is absent for the matches against Hearts (a) on January 26, Dundee United (h) on January 29 and Rangers (h) on February 2. If Riley McGree signs for the club, he would probably be in the same boat having been a feature of recent squads.

READ MORE: What Riley McGree brings to Celtic - Ange Postecoglou is getting a £3m dynamo with 'bite'

Other World Cup qualifiers

Unlikely to be affected: Cameron Carter-Vickers (USA)

The US men's national side has three qualifying fixtures coming up: first it's El Salvador in Ohio (January 27), then a trip to take on Canada in Ontario (January 30) before heading back to the US to face Honduras in Minnesota (February 3).

Currently second behind the Canadians, America are chasing a top-three finish in their section to avoid having to play an inter-confederation play-off.

It must be said, with four or five centre-backs seemingly ahead of him in the pecking order it is unlikely Cameron Carter-Vickers gets the call despite his stellar Hoops form.

Celtic Way: The US are second in their group ahead of games against El Salvador, Canada and HondurasThe US are second in their group ahead of games against El Salvador, Canada and Honduras

However, head coach Gregg Berhalter recently intimated that he could select an expanded squad for the three matches to combat Covid, so it's not absolutely outwith the realms of possibility that Carter-Vickers is considered.

If he is, he would miss the matches against Hearts (a) on January 26, Dundee United (h) on January 29 and Rangers (h) on February 2 with the first chance of a Celtic return being the match against Motherwell on February 6.

When will they be available again?

First of all, it's worth remembering that if more than three first-teamers are unavailable due to international selection a club can request fixture postponements

But assuming all dates stay as-is, all of Celtic's international travellers would qualify for the Scottish Government's 'elite sportspeople' exemption. 

If they are fully vaccinated they don't have to do a Covid test before returning to Glasgow but would have to complete a passenger locator form. After that it's a case of abiding by the test protocols put in place by the SFA-SPFL joint response group (currently daily). 

If any of the players called away are not fully vaccinated, government rules dictate they must self-isolate "when they are not at, or travelling to and from, a place where they are required to train or compete".

In short, the players chosen to go away on international duty will be available again pretty quickly after returning - provided they test negative, of course.