Six of Millwall's squad will be on international duty this weekend, with five a part of the final stages of FIFA World Cup 2018 Qualifying.
Along with Northern Ireland pair Conor McLaughlin and Shane Ferguson, the early season form of George Saville, Jordan Archer, Aiden O'Brien and Kris Twardek has earned the quadruplet call-ups to the Green and White Army, Scotland, Republic of Ireland and Canada respectively.
In Group C, Northern Ireland are assured of second place going into their remaining two matches against Germany (at Windsor Park) and in Norway, but can mathematically secure top spot and automatic qualification with two victories and two defeats for Joachim Löw's side.
McLaughlin and Ferguson look set to feature for Michael O'Neill's men, whilst Saville will be vying to win his first international cap.
The midfielder told millwallfc.co.uk of his call-up: "It's been a fantastic time for me and my family. Initially, one of the guys from the Irish FA rang me to discuss my potential eligibility and then I spoke to the manager about it.
"We decided that now was a good time for me to embark on my international career and I'm really excited and looking forward to joining up with the squad."
O'Brien's Republic of Ireland side welcome Moldova to Dublin on Friday night as they go in search of three points that will keep them in touch with the top two of Serbia and Wales in Group D.
Ireland then face a potential showdown for a Play-Off spot with Wales in Cardiff next Monday.
"I got a call after the provisional squad was announced to say "get your passport ready, you're coming away," so I had obviously made the cut," O'Brien explained.
He added: "I'm buzzing. I've never received that call from that senior of a level. I just can't wait to get out there. For me and my family, it's massive. I'm going to embrace it and play football with a smile on my face, enjoy it and do what I do best."
Meanwhile, in Group F, with England all but assured of a spot in Russia next summer, attentions turn to second place and a three-way fight between Slovenia, Slovakia and Scotland.
The Scots, complete with goalkeeper Archer, face two crunch clashes with their rivals in Glasgow and Ljubliana as they go in search of a World Cup Play-Off berth.
Canada, who lost out on qualification to next year's tournament to Mexico, face El Salvador in Houston, Texas. Twardek will look to earn his first cap in the friendly match.