SO, let’s get this straight.

Celtic were outclassed on their own park, lost two key players to injury, one which looked serious, committed some awful mistakes to lose a game and yet the stadium was rocking at the end as European football was secured.

The Scottish champions were well beaten and yet their nine points, plus RB Leipzig’s draw at home to Rosenborg – nobody saw that coming – proved to be enough for Brendan Rodgers’s side.

In all my years covering matches at this ground, there has never been a stranger one. It was literally glorious failure.

Would it have been dismal failure or where Celtic should expect to be if Rosenborg had not done them a huge favour?

There are arguments to be made for both points of view, I am somewhere between myself, although it is difficult not to keep going back to last January and the summer when both transfer windows closed with not a lot of good business being done.

However, they are through. Even if things had turned out differently, nine points including a win away is a decent return,

However, Celtic are in the draw, three wins is a decent return. But they are going to have to find something more in the last 32.

Still, the job was done.

1. Red Bull does give players wings – no wonder Salzburg are flying

The Green Brigade’s held up a banner which demanded: “Get this bull**** out of football”, a reference to how a such a big company can plough fortunes into a relatively average club from hardly a top European league.

They sit about a thousand points at the top of their league which, even they would admit, they have bought.

Alas, that is football in 2018. There are players at Red Bull FC who would never think of playing for an Austrian side but were lured by a massive pay packet, plus the club will outspend ‘bigger’ rivals in the transfer market.

This is what Celtic, and many clubs are up against. Money doesn’t guarantee success but it helps in football. Salzburg are a right, good team. They played some stunning stiff at times.

Celtic are hardly paupers but last night’s opponents are in another planet when it comes to spending money.

Now the Celtic fans know what Hamilton Accies feel whenever they face Brendan Rodgers’s team.

The Austrians were streets ahead. The Celtic players couldn’t be faulted for effort but they were second best.

Too many players had off nights when Brendan Rodgers needed all eleven to be near the top if their game.

Craig Gordon was having one of the best nights of his career when he made a huge howler for the second Salzburg goal. It was that kind of night.

To quote the manager, the club have stood still but what they really means it is moved backwards.

Salzburg looked as if they had more players than Celtic who did lose two players to injury which hardly helped.

With ten minutes or so to go, the place exploded with delight. It was Celtic's best ever defeat.

2. Scott Brown remains irreplaceable

What a lot of nonsense has been spoken about, less we forget, the current footballer of the year.

Those who have claimed Celtic are a better team without Brown should pipe down. He made a hugely positively contribution when he got on.

As Salzburg continually attacked, pinged the ball about, and got on every loose ball 40 yards from goal, Brown was badly missed. Sure, Salzburg scored twice when the 33-year-old was on the park but had he started then perhaps his team would not have been given such a run-around in the first-half.

That might have made a difference. Brown might be in his last season but he is still in many ways the man.

3. Football needs to take a leaf out of rugby’s book when it comes to head knocks

When Mikael Lustig hit the ground after only a few minutes, team-mates frantically called for the medics to tend to the stricken Swede.

Lustig looked out cold but after some attention, gingerly got to his feet and played on. It must have been his call and one he should not have been allowed to make.

He was brave but for five minutes or so wandered about the pitch as if he’s had a good drink in him. There is no way he should have been allowed to carry on.

Lustig complained to the bench that he was having a problem with his eyesight and was soon subbed. Now, I am no doctor but if a human is knocked out, or close to it, they shouldn’t have to play football.

In rugby, players got off for an examination if there is any hint that they’ve taken a blow to the head. That’s sensible.

4. Tom Rogic is a funny player

When on his game, there are few better sights at Celtic Park than the Australian dancing past tackles with such style.

He could turn a defender in a phone box when on form. He could not have been more off it in this game and he’s such an important man with the way Celtic play that the team suffered.

Rogic is a talent. But he does blow really hot and cold. The big man must have been freezing last night.

5. Leigh Griffiths will have been heartened by what he saw

He wasn’t there in person but the troubled player was in the minds of the supporters who canted his name, fittingly, after nine minutes.

A banner on the terrace read “It’s OK not to be OK” which is a fine sentiment and one which thankfully more people are coming to terms with.

Nobody really knows what is going on with Griffiths but we can hazard a guess, and when thing get on top of even the strongest character, that’s when the black dog begins to bark.