Fans of football have been greeted with many a cliche over the years.
In the case of the balance of this tie, it is true.
It is not over until the fat lady sings.
The San Siro is an intimidating ground to go to at the best of times. It regularly hosts matches featuring two of the biggest teams in Italy.
The sad fact is, in recent times, it has lost some of its lustre.
Tottenham came to the San Siro buoyed by two recent comeback wins in the Premier League. They could also count on a late rally against Inter in this same ground during the group stages.
And they got off to a flier here. Within the first minute, they had possession as well as bodies forward in the box.
What followed for the first 20 minutes or so was a series of terrible Milanese defensive errors. At a few points, it would have been fair to say a game of pinball was taking place within the box.
Errors at the back were not the only thing hindering Milan though. It has been a long time since I have sen Milan give possession away so cheaply and, worse, so regularly.
No sooner had they cleared their lines than they were back under the cosh with an assault of white jerseys.
As a fan, watching the first half was akin to what I must imagine torture feels like. Even without the artistry of Antonio Cassano and the recent addition of steel provided by Mark Van Bommel, you would have thought the Milan midfield would have enough in the tank to cope.
You would have thought wrong.
In the first half at least, Milan's midfield was completely and totally overrun. The formation Spurs started with exposed the most important weakness this Milan side have: a lack of width.
Darting runs by Aaron Lennon nearly cost Milan dearly in the opening exchanges. Milan didn't learn.
Spurs pulled the three-man midfield of Milan all over the pitch in the first half hour. With their full backs pushing up and pressing, at times the AC midfield was outnumbered two to one.
Amazingly, the score remained nil-nil at halftime. Watching an English-biased, and that is not a typo, channel, you would have thought Spurs had completely dominated the game.
In terms of possession, Milan had the edge. In terms of meaningful shots on goal, it was honours even.
Watching the game on a biased, English-speaking channel, you would be forgiven for thinking that Spurs had hit the target with shot after shot that had been cleared off the line.
The facts are they had no clear chances the first half.
The second half may provide a better reflection on how this tie may end up. Milan were the better side after the break.
Heurelho Gomes will look back on this birthday fondly as the day he made one excellent save, but also one extremely lucky save against AC Milan at the San Siro.
For the majority of the second half, AC had Spurs pinned down in their own half. The excellent Spurs defence on the night were forced into resorting to the kind of "clear the lines at whatever cost" the entire Milan team seemed to be using in the first half.
There was simply more menace to Milan in the second half. Players were pressing for the ball and harassing Spurs' players.
It may have been a case of too little, too late.
The fact is, there is still all to play for at The Lane. AC can still get a positive result. Spurs scored with their only real chance of the game. Gomes denied Milan twice.
Still all to play for.
On a side note, I hope we have a clean game in the return leg. Some of the behaviour tonight was disgraceful, and even as an AC fan, I hope Rino gets a healthy ban.