They sing about the heat of Lisbon. But there is nothing in verse about the suffocating temperatures in Seville. Or anything that recalls the sight of Neil Lennon, in an unseasonable early summer Spanish heat wave, warming up complete with head-to-toe black under-armour gear, unwilling to part with his lucky UEFA Cup tradition that he sported through every round of the 2003 tournament.

But what is notable these days is that Lennon’s thermostat has been turned down.

There is much football to be played this month which could affect the prism through which Lennon is viewed, but the most striking thing about the 48-year-old is the manner in which he has distilled his trademark candour into a significantly calmer version.

The evidence would suggest he is all the more potent for it.

If it seemed like Lennon was on his best behaviour when he was asked to steady the ship following Brendan Rodgers’ departure from Celtic in February, the mask has yet to slip.

However, if there is anyone who might have a go at pulling it off, one’s money might be safe with Willie Collum and a Hampden final against Rangers next weekend.

But, on current viewing, it would be difficult to escape the notion that the more subdued version of Lennon has enhanced his managerial hand.

It is too early to talk about making an impact on the latter stages of a European competition given the quality which Celtic could yet meet in the knockout stages. But what can be argued over these last few months is that as a team, Lennon’s side have grown in stature and composure in this arena.

The experience he has brought virtue of his own time playing at this level cannot be underestimated.

If some of Celtic’s defeats in the Champions League were bruising experiences in recent seasons – 34 goals conceded and just seven scored in two campaigns – there is consideration to be afforded to what has been learned from that exposure with a spine of players who have largely stayed the same.

Celtic’s final Europa League game next month will be Lennon’s 50th European game in the Parkhead dug-out. It’s doubtful that he will have a more comfortable night.

There has always been an alchemy between Lennon and Celtic, particularly on a European front, but this season’s stats have been particularly impressive. The exit to Cluj in the Champions League qualifying stage remains the only black mark but there has been considerable atonement for that.

Of the 48 teams in the Europa League, Celtic are second in points only to Seville. Thirteen points from a possible 15, qualification at the earliest opportunity and winning a group with a game to spare is unheard of in Scottish football.

Swatting aside Rennes, regardless of their whipping-boy status in the group, with a makeshift frontline underlines the layer that lies beneath the regulars but it is the manner of the performances that auger well.

But what Celtic’s progression also does is rubbish the theory that Lennon is some old-school relic. The idea that some of the Celtic support snubbed their noses at Lennon for an apparent dinosaur philosophy seems absurd just a few months down the line.

Ryan Christie is playing out of his skin and with 14 goals this term he is on a par with Odsonne Edouard.

Lennon might never better that win over Barcelona in 2012 but he has returned some extraordinary night to Celtic in a European context.

And if talk of co-efficient tables creates an urge to stifle a yawn, the reality is that an invite to the Champions League dance for two Scottish teams fairly lifts the spirits.

There remains a significant way to go in that regard, while staving off the threat of a slide into UEFA’s forthcoming third-tier tournament is absolutely vital too. But the co-efficient mountain Celtic and Rangers have scaled this season has to be applauded.

Hauling Scotland up the table to 15th would have looked like too much of a reach at the start of the season so for both to engineer such an elevation is quite exceptional.

With at least four European games remaining – more if Rangers qualify too - the opportunity is there to cement that place and see just where it leads.

Those who have lived through the recent experience of Scottish clubs stuttering through European campaigns will know about the lasting damage of poor campaigns. We can only hope the converse is true as Scotland look to plant a flag again.

Lennon has certainly earned the right to wave his.

And another thing

So, could a glorious reunion be on the cards?

Away from home for the first time in his life, a paternal arm around the shoulder from Brendan Rodgers down in London might ease any homesickness on Kieran Tierney’s part.

There were certainly a few raised eyebrows yesterday – and a few twitchy Leicester fans – as the Arsenal job became vacant following the dismissal of Unai Emery.

Rodgers was hardly at pains to shut the door on interest from the London club.

“It’s a natural thing, when you’re doing really well somewhere, that someone else will want to take you away from there,” he said. “Arsenal are a fantastic club and I’m sure they’ll have a good idea of who they want as their next manager.”

Having engineered quite a turnaround at Leicester in his nine months at the club, Rodgers’ work was never going to go unnoticed.

And, as the quick exit from Celtic showed, one can never be choosy about just when clubs come calling.

Rodgers might well incur the wrath of the Leicester support were he to head off now but he has a thick enough skin to be able to cope with any flak that would come his way. And as he would doubtless suggest, it’s a move that might not present itself again.