About a year ago, in a tapas bar here in Seville, I noticed that the lady at the table next to me was feeding her year-old baby with a plastic spoon, cooing "Mucho Beti'!" in a gently encouraging manner at every mouthful. Meanwhile, on the other side of the table, her husband was keeping up a sotto voce stream of counter-propaganda. "But don't you think green and white are ugly colours? Imagine having to wear them the rest of your life. Is that what you really want?" etc. etc. Both parents - and several watching onlookers - were giggling like mad. The child itself declined to comment.

And that, for me, sums up the football rivalry in this city. Fierce enough to make you want to brainwash a one-year-old, but not so out-of-perspective that you can't 1) marry someone from the opposite side of the fence, and 2) hugely enjoy the joking that inevitably ensues. Andalucíans have a word for this: guasa, which means something like taking the mickey (ie making fun). Like in Britain, this is part of day-to-day life here and, as you can imagine, football is very often the subject.

So, Béticos tease Sevillistas about all coming from pijo (posh) parts of Seville like Los Remedios and Nervión, while they think we're a rabble of country bumpkins. They complain too much, are never satisfied and are bad losers, while we simply don't take football seriously enough. And so on. But Béticos and Sevillistas are married to each other, are brothers and sisters, fathers and sons, mothers and daughters, work colleagues, best mates, Facebook friends and fishing buddies. Even Betis legend Rafael Gordillo says his wife and daughter are Sevillistas. It's part of what makes living in this city so much fun.

All of which means that what happens on the pitch will only be part of the derbi story. At one company where I teach, the employees are taking part in a Betis-Sevilla football match tomorrow morning. My lovely Sevillista Spanish teacher told me this afternoon that she's almost too nervous to talk. All over the city tonight, people are confessing to their friends that they feel sick with anxiety.

Of course, in recent years this kind of tension has occasionally spilled over into something very like violence - what with the bottle thrown at Juande Ramos, assorted directors' box spats between Del Nido and Lopera, regular skirmishes between ultras in the streets. But this time there's a real sense that the occasion is returning to its roots.

AS newspaper, in an article entitled "Betis-Sevilla gets back its old values", has summed up the mood nicely.

"An attempt has been made to get rid of the antagonism, the thrown bottles, the violence, the sense of a city under siege that once surrounded the game," writes Juan Jiménez. "Sadly, it took the death of Antonio Puerta [the young Sevilla player whose heart attack was mourned right across Seville in 2007] to make the city, the clubs, the fans, everyone have a good look at themselves. Now Lopera has also gone... And so here we today. On the day before the derbi here in Seville only football will be talked about. Two training sessions behind closed doors, and time to prepare. Sevilla will get together the night before and then train in public [at the Sánchez Pizjuán] so their fans can give them a lift. Betis are promising an unbelievable welcome for their team. Both clubs have been outstanding in the build-up, they've done everything the city could want and haven't excluded anyone. Now it's the turn of the players to put on a gigantic show. And for the supporters to match them. The derbi is here."

Just 26 hours to go.