The good old days. While it might seem an alien concept to many now, it was not that long ago that Celtic were able to compete with some of the best teams in Europe. This was a prime example.
In November 2001 Celtic faced off against Valencia in the third round of the UEFA Cup, the precursor to the current Europa League. They played out two incredibly tight games, with penalties ultimately required to separate the sides.
This was no average Valencia side either. They had just reached two consecutive Champions League finals, losing to Bayern Munich on penalties only a few months prior to this game.
Under Rafael Benitez, later that season they would go on to break the Barcelona-Real Madrid duopoly in La Liga, being crowned Spanish champions. They would repeat the feat two years later, with only Atletico Madrid emulating their achievement since.
With the first leg in Valencia finishing 1-0 to the home side, the tie was finely balanced heading to Glasgow. Celtic would go on to put on a masterful display, and truthfully could have run out comfortable winners.
What a team this was, featuring Henrik Larsson, Paul Lambert, Chris Sutton, Stylian Petrov. They pushed one of the best teams in Europe at the time all the way, and should have beaten them.
After the game, manager Martin O'Neill was very upbeat about his team's efforts.
Naturally the lads are desperately disappointed but they have absolutely nothing to be ashamed of and I am very proud of them all.
We have come a long way and we have discovered a taste for it all so I hope we can improve still at this level in the future.
Of course they would go on to do just that, reaching the UEFA Cup final the following season. On that day they were bested by a rising young manager by the name of Jose Mourinho, with that Porto side going on to win the Champions League 12 months later.
In many ways, these days seem like a distant memory. While domestic dominance has been welcomed by their fans, this type of European pedigree has been sorely lacking in recent times. The landscape of football has changed, and this has gone against Celtic.
While they may no longer be able to compete with the European elite, their continental journey is still ongoing this season. Eliminating Copenhagen next month could be the first step in getting the club back to where they belong.