Today is likely to be the most exciting day in east London since Danny Dyer decided to move out to Essex. Yes, it's Leyton Orient v Arsenal, a repeat of the 1978 FA Cup semi-final and a chance for the Os to exact revenge on the Gunners for being much, much better than them on that fateful day and throughout their entire history.
Here, then, are the seven things that Arsenal need to be wary of:
1. Dean Cox
Yes, the Arsenal defence might have stopped Lionel Messi scoring midweek, but it's unlikely they've had to deal with a 4ft 7in winger hiding behind a corner flag and then popping out to headbutt someone in the knee. Already this season the man they call 'Tiny' has scored seven goals and made 15 assists - and that's one more than a certain Cesc Fabregas has made over the same period.
2. The food
As anyone who's ever eaten a burger at Brisbane Road (and lived) can testify, food isn't one of Orient's strong points. Should the Arsenal team decide to indulge in any pre-match nourishment at the stadium, then it's likely that Theo Walcott won't be the only player with the driving runs.
3. Jimmy Smith
Previously a player so bland that he was once asked to endorse a new brand of mild tofu, the midfielder has recently turned himself into a formidable goal machine. If he can get his head on the end of a few crosses he may well accidentally skew one of them into the net.
4. Orient's 'two-ball' trick
Unlike at proper clubs, the Leyton Orient crowd delight in throwing one ball back on to the pitch just as play has restarted with another. And while Arsenal might be all big and clever with one ball, they're probably less used to defending against two, which could play to Orient's advantage.
5. Jamie Jones
All of Orient's goalkeepers throughout their entire history have had a pronounced weak spot. Ashley Bayes's was his inability to collect crosses; Glenn Morris's was his kicking; Stuart Nelson's was his madness; Peter Shilton's was his obesity; and Mervyn Day's was, you know, saving stuff. Not Jamie Jones, though - a hero between the sticks and a player who might just be able to prevent Arsenal scoring more than seven.
6. The manager
Arsene Wenger may be a master tactician, but could he devise a sound defensive strategy if he was forced to play Elliott Omozusi at centre-back? Probably not. Big Russell Slade, on the other hand, has tranformed Orient into a delightful, ball-playing team who've lost just once in the last 20 games and who keep defying the traditions of the club by winning games by more than a one-goal margin.
Arsenal may claim Prince Harry, Piers Morgan, Jay-Z and Dido as supporters, but can their team be inspired by the man who wrote the moving and historically accurate musical Joseph And The Amazing Technicolour Dreamcoat? I think not. Yes, Andrew Lloyd Webber will be cheering on the Os on Sunday and hoping, like me, that any dream will do.