Already on a booking, Bergvall brought down Tsimikas but play continued with Liverpool retaining possession.

However, Tsimikas was then off the pitch receiving treatment when Bergvall scored to seal a 1-0 first-leg victory for Spurs.

The International Football Association Board's Laws of the Games state: "If the referee plays the advantage for an offence for which a caution/sending-off would have been issued had play been stopped, this caution/sending-off must be issued when the ball is next out of play.

"However, if the offence was denying the opposing team an obvious goalscoring opportunity, the player is cautioned for unsporting behaviour; if the offence was interfering with or stopping a promising attack, the player is not cautioned."

The crucial part of the above is the final sentence. The offence - the foul by Bergvall - was interfering with a promising attack.

If referee Stuart Attwell did indeed play advantage then, applying the above, he did not have to go back and caution Bergvall.

But the laws also state "advantage should not be applied in situations involving serious foul play, violent conduct or a second cautionable offence unless there is a clear opportunity to score a goal."

Was this a clear opportunity to score? Debatable.

At the weekend, Tottenham boss Postecoglou described himself as "the angriest he had been" during the 2-1 loss to Newcastle after Anthony Gordon's equaliser had been allowed to stand after a handball in the build-up.

After Wednesday's game, he said: "I didn't think the decision was right about the handball. But I said, it's very hard at the moment, it's very confusing, to understand certain elements of the game.

"Now we've been told consistently in the last few weeks, because I've been screaming about it from the sidelines, because a lot of teams have got away with a lot of fouls with us, without bookings, because the referee plays advantage.

"We've been told consistently that if we play advantage, as long as it's not a cynical foul, then the player does not get cautioned. So that's been relayed to us on a weekly basis. Because we feel like that's been happening."

Liverpool boss Slot had been furious with the decision at the time, and remained frustrated with it after the game.

He said: "The decision he [the referee] made had a lot of impact on the result. There's not a lot I can say from that.

"The fourth official told me why he thought it wasn't a second yellow and he heard that probably from the referee. What we can say about it is that he said he didn't stop the counter-attack, every manager would say they prefer the second yellow than a counter-attack that goes on.

"It is what it is, we hate to lose but the positive is that it is better to lose when there is a second leg."

Postecoglou has made it clear several times since managing in the Premier League that he is unhappy with where certain elements of the modern game are heading.

During Wednesday's match at Tottenham Hotspur Stadium, a decision by the video assistant referee (VAR) was announced to the stadium for the first time in England, after Dominic Solanke had a second-half strike ruled out for offside.

After the game, Postecoglou embarked on a lengthy critique of football and where it could be heading.

He said: "I'm really surprised at how, what's the word I'm looking for, how people in this country are so easily letting the game change so much so quickly. It's changed more since VAR has come in since I've been involved than in the past 50 years.

"We never used to debate offsides, we never used to debate handballs, we never used to debate holding in the box, we never used to debate so many things.

"I mean, did everyone really love the announcement today? Did that give you a real buzz about, you know, I mean, seriously, but now I'm, and again, look, I understand, my understanding of it is, this is what the people want. That's what I keep getting told.

"I understand that. I understand VAR is going to be there, technology's going to be a part of life, but it's like my wife and our kids. We know technology but she limits screen time. Why? You know, slow things down, I think.

"We've just got to be careful about constantly - why do we want to change the game so much? And I know I'm going to be the old bloke in the stands that keeps shouting 'boo' every time and I'll be the only one, but I just thought people would be a little bit more protective about the sanctity of the game.

"That's what I was talking about. I wasn't criticising referees, I wasn't. I've never criticised, I didn't think the decision was right, but it's just the way the game, I think there's a lot of confusion at the moment.

"That's my belief that the game is changing on the basis of technology, and I'm saying why isn't anyone speaking up about it? Especially in this country who, for all intents and purposes, you feel, you guys think you're custodians of the game, you've got a song that says 'it's coming home', this is your game, and yet it takes an Aussie from the other side of the world to be the one that's most conservative about changes."