MARTIN O’NEILL was left impressed as Rangers made it all the way to last month’s Europa League final – and with group stage Champions League football guaranteed at Celtic next season, he believes his old club must now follow suit and leave their mark on Europe.

Giovanni van Bronckhorst’s men punched above their weight on the continent last term, picking up some notable scalps on their way to an agonising penalty shoot-out defeat at the hands of Eintracht Frankfurt in Seville.

It was the same city where O’Neill suffered European heartache during his stint as Parkhead manager all those years ago. Back then, money was flowing into the game as the two halves of the Old Firm vied for supremacy on an annual basis, constantly driving up each other’s standards through relentless competition.

Reflecting on Rangers’ run to the final of Europe’s secondary club competition, O’Neill sees shades of the way Scottish football used to be. After seeing the Govan outfit going up against some of the continent’s biggest hitters and leaving them with a bloody nose, the 70-year-old reckons it is now Celtic’s turn to pick up the baton and perform well on Europe’s biggest stage – particularly that the perilous qualifying rounds no longer have to be navigated for the Scottish champions.

“There has been an upsurge in the Scottish game with Celtic winning the league and Rangers getting to the Europa League final,” O’Neill observed. “European football matters a good deal, obviously. You look at the Champions League but you look at the Rangers run.

“People sat up and took notice, especially the Dortmund win and now it’s over to Celtic. They go straight in to the Champions League group stages. When was the last time a Scottish side did that – 2008?

“Did I help [my successor] Gordon Strachan get there? I don’t think he ever thanked me!

“It’s huge. I think that is the biggest thing, not having to play teams you would beat in October but have difficulty in the third week in July. Those games used to annoy the heck out of me. Going to Lithuania or something, those games really concerned me.

“People would say, ‘Ach, you’ll win this easily’. No, you’ve had two weeks training and you are straight in.

“Going straight in is a huge boost for Celtic. Your whole outlook changes. You are not under pressure in pre-season, you are ready to go. It’s fantastic.”

Avoiding potentially hazardous qualifiers is one clear benefit of Scotland’s improved European coefficient but there are other tangible benefits that accompany Celtic’s return to the Champions League proper.

Being a well-supported club with a seat at Europe’s top table makes signing for the team a far more attractive prospect. Higher salaries can be dished out to more talented players and the result, O’Neill says, is that Celtic will find it a little easier recruiting players in the summer transfer market.

He explained: “Is it a big selling point? Absolutely. The club – and the same goes for Rangers – is the star and is its own selling point. But going straight in to the Champions League is another story.

“If I’m a player plying my trade in the Dutch league for example, which is very strong, but if the chance to get in to Celtic and straight in the Champions League would be something to really think about.

“That’s where you boost your own image if you do well enough. It’s an easier task to recruit when you have that.”

For all that supporters have enjoyed Ange Postecoglou’s revolution at Celtic Park thus far, there is one notable black mark against the Greek-Australian’s name: Europe. It is not an uncommon problem for those who occupy the Parkhead hot seat.

The Glasgow club were knocked out of the Champions League qualifiers at the first time of asking as they were defeated by Midtjylland before a third-placed finish in a difficult Europa League group saw them drop into the Conference League, where Norwegian champions Bodo/Glimt comfortably triumphed over the two legs in the first knockout round.

It means that O’Neill remains the last man to win a European knockout tie as Celtic manager, excluding qualifiers. The 1-0 aggregate victory over Barcelona in the UEFA Cup in March 2004 was the last occasion where the Parkhead outfit defeated a continental foe over two legs and O’Neill accepts that improvement is required on this front.

The former Republic of Ireland manager understands that Postecoglou opted to focus on domestic matters last season but now that supporters have seen what the team are capable of, O’Neill insists the club’s ambitions must grow to match the fans’ expectations.

That might mean swinging the axe and bringing in new recruits but as the recent decisions to release long-serving midfield duo Nir Bitton and Tom Rogic have shown, Postecoglou isn’t afraid to shy away from the big decisions.

“I think after the start last season the manger had to almost disregard Europe and concentrate on the league,” he said.

“That’s what he did and now the expectation is higher. They are in the Champions League and of course there will be great nights. But they have to address European football now and compete. Celtic’s results in recent years have not been good enough.

“I just hope he doesn’t phone me for any advice! I think he’ll know that himself and it’s about trying to get a better players for that level.

“Obviously he’ll show loyalty to the ones who got them there but in his own mind he’ll be thinking about carrying it further. I’d think he’d be trying to strengthen the side to compete in Europe.”

Martin O'Neill was promoting Premier Sports live and exclusive coverage of Armenia v Scotland (8th June) and Republic of Ireland v Scotland (11th June). Premier Sports is available from £9.99 per month and available on the platforms Sky, Virgin TV, Premier Player and Amazon Prime as an add-on subscription.