With both Northern Ireland and the Republic of Ireland on the verge of a return to the World Cup finals, we look ahead to five pivotal international matches not to be missed this week, live on Sky Sports.
It has never happened in World Cup history, but having both taken part in last summer's European Championships, it is possible that Northern Ireland and the Republic of Ireland could both be heading to Russia next summer.
Switzerland travel to Windsor park, while Denmark welcome Ireland to Copenhagen in the first legs of the play-offs this week. Northern Ireland are a force to be reckoned with under Michael O'Neill, having achieved an all-time high FIFA ranking in September, while the Republic will still be buoyed by their late revival in their European Qualification Group. You won't miss a kick from either play-off live on Sky Sports.
Elsewhere, Sweden face the tough prospect of overcoming Italy over two legs, while Croatia must battle past Greece, also live on Sky Sports. Scotland's friendly with the Netherlands is important for an altogether different reason. Here we look ahead to a crucial week of international football.
Northern Ireland v Switzerland - Thursday 7.45pm - Sky Sports Main Event
Gone are the days when the Green and White Army were simply there to make up the numbers. The defeat to world champions Germany last month was their first competitive home defeat since they lost 4-2 to Portugal in September 2013.
If it wasn't for the relentlessness of Germany, O'Neill's men could have qualified automatically. Indeed, their record of six group stage wins is their best-ever total in any World Cup Qualifying campaign.
Northern Ireland's play-off opponents Switzerland are ranked 11th in the world. They won nine of their 10 qualifiers but defeat in their final game against Portugal saw them finish second in Group B.
"It's the highest seed, but I'd prefer them to Italy and Croatia," said ex-Northern Ireland international Iain Dowie.
Having kept a clean sheet in seven of their ten qualifiers in Group C, breaching Northern Ireland at Windsor Park in the first leg may be difficult, but will they have enough to pick up the victory that would see them put one foot in the finals?
Denmark v Rep. of Ireland - Saturday 7.45pm - Sky Sports Football
All seemed lost for the Republic of Ireland after the home defeat to Serbia back in September. Securing that play-off spot was in Wales' hands, with it all coming down to a winner-takes-all clash in Cardiff in the final Group D showdown.
A draw could have been fine for Wales to finish second, but James McClean was once again the hero for the Republic, securing the win that saw Martin O'Neill's men snatch that play-off spot, seemingly out of nowhere.
Ireland came through a two-legged play-off against Bosnia and Herzegovina to qualify for last year's European Championships in France and O'Neill believes that will stand to his players as they attempt to reach their first World Cup since 2002.
"We can draw from that experience," he said. "We had two very difficult matches against Bosnia."
Opponents Denmark lost two of their opening three qualifiers but rallied to finish second behind Poland in Group E. They have won three of their 11 competitive fixtures against Ireland, with the Republic winning four. It seems a favourable draw, now Ireland have to get off to a positive start in the first leg in Copenhagen on Saturday.
Sweden v Italy - Friday 7.45pm - Sky Sports Football
Having battled hard to earn second spot in Group B at the expense of the Netherlands, how were Sweden rewarded for their efforts? Well, a play-off with four-time winners Italy, of course.
Italy are not the force they once were, but still represent tough opponents. It was always going to be difficult to top Spain in Group A, with only Switzerland finishing with more points of the second-placed teams.
The two sides last met at Euro 2016, with Italy running out narrow 1-0 winners to top their group and send a Sweden team featuring Zlatan Ibrahimovic home early.
Croatia v Greece - Thursday 7.45pm - Sky Sports Mix
On paper, this almost looks like a shoo-in for a talented Croatia against a Greece side in very indifferent form, but with all the turmoil behind the scenes, expect a few surprises.
After their draw with Finland last month, the Croatian Football Federation made the decision to sack coach Ante Cacic, with Zlatko Dalic installed as his successor less than 48 hours before the do-or-die match against Ukraine. The players responded with a superb performance away to keep their World Cup hopes alive.
Greece also have a proven track record in such fixtures, having twice managed to qualify from play-offs against Ukraine and Romania.
Scotland v The Netherlands - Thursday 7.45pm - Sly Sports Football
Sandwiched in the middle of the play-off process is a friendly which would normally not hold the greatest of significance, but two teams in transition will be using Thursday's friendly at Pittodrie to assess their future potential.
Scotland are managerless, and will quickly be looking to put their World Cup heartache to the back of their minds, having come so close to snatching a play-off spot. Interim head coach Malky Mackay has named eight uncapped players with skipper Scott Brown, whose future was in doubt following the end of the failed 2018 World Cup qualification campaign, also included.
The Netherlands are a team with a point to prove as well. The forefathers of Total Football are in real disarray after failing to qualify for successive tournaments for the first time in 22 years. Plenty of points to be proven.