Over 152,000 fans, 2,000 staff, four teams, four sets of goalposts and zero prawn sandwiches. Croke Park will this weekend host the biggest, most high-profile double-header in its long history as a sports venue, which stretches back to before the founding of the GAA in 1884.
Tonight, the Irish soccer team take on France in the opening tie of a two-leg World Cup play-off, with a trip to South Africa next summer as the glittering prize.
Tomorrow, Brian O'Driscoll and his Irish rugby team take on Australia in the opening match of the Autumn International Series. In between the games, the staff and management in Europe's fourth biggest stadium will have just 12 and a half hours to "flip over" from World Cup soccer to international rugby.
And this all has to be done while respecting the agreement with local residents that no heavy trucks or machinery operate between midnight and 8am.
From VIPs -- including the Taoiseach Brian Cowen and the French Minister for Sport -- to corporate guests, broadcasters, the four teams and regular punters, Croke Park will host a dizzying array of people and nationalities over 48 hours.
But Roy Keane, no doubt watching at home with Triggs the Labrador and Izac the German Shepherd, will be delighted to hear that there won't be a prawn sandwich to be had anywhere in the stadium.
"No, there are no prawn sandwiches on the menu; that's a deliberate response to Roy Keane," quips stadium director Peter McKenna.
Mr McKenna and his stadium operations manager Alan Gallagher are remarkably relaxed ahead of their big weekend.
The planning process started 18 months ago when the rugby international was confirmed, and preliminary planning with the FAI started months ago, ahead of a possible World Cup play-off.
"We depend very much on the co-operation and professionalism of the rugby and soccer associations and on very careful forward planning," says Mr McKenna.
"Most of what we actually need in terms of catering and so forth is actually front-loaded into the stadium during the week, so it's all here and ready to go," adds Alan Gallagher.
The major work on transforming the pitch starts at 10pm tonight, when a small team of groundsmen will begin changing the markings (rugby pitches are slightly shorter and broader than soccer pitches) and setting up the different goalposts.
And their secret weapon is a new type of pitch marking system known as "Magic Paint", a paint that can simply be hosed off with warm water, allowing the turf to be fully re-marked within hours.
Some potential problems will require a more traditional approach.
The gardai and security staff will conduct a full search of the ground before midnight tonight to ensure that no soccer fan who wants to see the second part of the double-header for free is tempted to have a Croke Park sleep-over.
"Tickets are expensive and hard to come by, so we will conduct a full search of all areas of the stadium to ensure we don't have unwanted guests for the night," says Mr McKenna.
With two major matches and two full houses of 76,000 (reduced from 82,300, thanks to the temporary seating on the Hill) the weekend's official timetable is a packed schedule.
8am: Stadium opens for business, television outside broadcast units conduct final tests. Security and catering crews begin arriving.
10.30am: French soccer team arrive for a pitch walkabout.
Midday: Stadium safety officer Tony McGuinness begins initial stadium walk and sign off as catering, security, stewards, turnstile and other staff begin work.
6pm: Public turnstiles open (corporate guests have already been arriving for up to one hour beforehand).
8pm: Ireland v France.
9pm: Night crew enter stadium.
10pm: Divot crew begin work. Line removal and soccer posts come down. Advertising boards are removed -- Hill and Canal Ends first to allow access for posts. Floodlights set to night setting. Public level areas are cleaned. Changeover of dressing rooms and team warm-up areas.
11pm: Sky personnel leave stadium. Rugby posts up. Catering restock. Corporate level clean-up begins.
Midnight: Groundsmen mow length of pitch only. Begin signage change. All FAI material leaves stadium by midnight. Stadium locked down for the night.
1am: Contractor/Ops meeting. Confirm FAI de-rig and IRFU set up.
2am: Changeover of washroom posters.
4am: Begin moving advertising scrollers and A Frames into match positions.
5am: Begin mowing the width of the pitch.
6am: Start pitch advertising painting. Go/No Go until 9am.
7am: Sign off sheet to safety officer Tony McGuinness. Floodlights off.
8am: BBC personnel arrive. Line marking. Floodlight generator refuel. Waste compactors and balers emptied. Initial stadium walk and sign off by safety officer.
1pm: Finalise match say set up. Public turnstiles open.
3pm: Ireland V Australia