HOW to improve upon perfection was the question which Brendan Rodgers was faced with as his Celtic side prepared for the start of the new season this summer.

Going undefeated domestically and winning only the fourth treble in their history – on the 50th anniversary of the Lisbon Lions’ historic 1967 European Cup triumph over Inter Milan no less – was celebrated joyously by everyone associated with the Parkhead club back in May.

There are, though, consequences to that sort of success. Rodgers and his players had an awful lot to live up to when the 2016/17 campaign kicked off in July as a result. Failure to match or improve upon their heady achievements of the previous term would have led to inevitable criticism. The demands on them to move forward were great.

But “The Invincibles” have risen to the considerable challenge admirably. They defeated Motherwell comfortably at Hampden nine days ago to retain their Betfred Cup trophy. Their 5-1 win over the same opponents at Celtic Park on Saturday has since extended their unbeaten run to 67 games.

Now they have the chance to top their accomplishments of last season by securing European football after Christmas.

Should Celtic defeat or draw with Anderlecht in their final Champions League group game in the East End of Glasgow this evening they will finish third in their section and progress to the knockout stages of the Europa League.

Even a defeat against the side they beat 3-0 away from home in the Constant Vanden Stock Stadium back at the end of September may be enough.

Rodgers’s men may have failed to emulate what Gordon Strachan’s side memorably did twice in 2006 and 2007 and what Neil Lennon’s team famously did in 2012 and book a place in the last 16 of the Champions League.

However, as their matches against Bayern Munich away and Paris Saint-Germain both at home and away have highlighted, competing with the continent’s elite is far harder now than it was for their predecessors given the growing disparity in spending power.

The best which they could reasonably have hoped for after being drawn alongside Paris Saint-Germain and Bayern Munich, two of the favourites for the competition, back in August was to finish ahead of Anderlecht in Group B.

If they achieve their goal – and there is no guarantee of that despite the disarray which their opponents find themselves in both on and off the park at the moment – they can be rightly proud of their efforts.

The heavy defeats which they suffered to Saint-Germain, who fielded the most expensive forward line ever assembled in Edinson Cavani, Kylian Mbappe and Neymar, both in Glasgow and Paris and the embarrassing loss which they slumped to in Munich against Bayern, who were, with Robert Lewandowski and Thomas Muller in attack, no slouches going forward themselves, were difficult to take.

However, getting the result they desire against Anderlecht tonight would be an undoubted step forward for this group of players and their manager.

Their draws with Manchester City both at home and away and their draw with Borussia Moenchengladbach away last season were admirable given the superior quality of the sides they were facing. Some would possibly even argue they have regressed. Rodgers would disagree.

“I’ve been really pleased with a lot of elements of how we have approached it this year,” he said yesterday. “It’s a huge task for us to get there.

“It might mean nothing, because most people only look at the scoreline, but I looked at our numbers after the PSG game away from home (Celtic lost 7-1 in the Parc des Princes last month).

“When I dig deeper and look inside it, we made over 400 passes in that game. In the game away to Barcelona the previous year, we only had around 150 passes.

So that told me a story about the belief of the players in their improvement at this level. What doesn’t change is the quality of your opponents, of course.

“But it’s allowed me to say: ‘Okay we are getting a greater belief to play in these arenas’. You have to defend a little better than we did and hope the opponent has an off night.

“For us to get a victory away at Anderlecht previously was important for our confidence. Tactically and technically, the players were excellent in the last home game against Bayern Munich. In the coming years, we have to see some of these games through so we can get a result on the back of a good performance.”

If Celtic once again overcome Anderlecht, who reached the quarter-finals of the Europa League last season, and go through then they may get a chance to do exactly that.

It would certainly be interesting to see how Scott Brown, Craig Gordon and Moussa Dembele fared against a far lesser standard of opponent than some of those teams they have faced in Europe during the past couple of seasons.

There will still be some exceptional sides from major footballing nations involved, but Rodgers and his men would certainly fancy their chances given the experience they have gained.