5 things we learned from this week's Champions League action

1. Money does not always guarantee success in football, even in cases where David confronts Goliath

(Celtic’s Victor Wanyama celebrates scoring during the UEFA Champions League match at Celtic Park – Lynne Cameron/PA Wire/Press Association Images)

This sporting truism has been highlighted more than ever this week, with Celtic beating Barcelona, despite a significant gap existing between the two teams financially.

Celtic showed considerable intelligence during the game, taking full advantage of their rare attacks and scoring twice even though the majority of the match took place in their own half.

Moreover, Neil Lennon’s men demonstrated a remarkable level of discipline, defending doggedly and with complete concentration for the full 90 minutes, while not picking up a single booking in the entire match.

The result does not change the widely held belief that Barcelona are practically guaranteed to qualify for the next round, while Celtic may yet struggle to progress.

Yet it hardly mattered last night for the Parkhead faithful, as they witnessed one of the most memorable moments in the esteemed club’s history.

And perhaps most importantly, the result, coupled with their brave performance away to the Spanish side, has given Scottish football a much-needed boost in credibility, on the back of the recent finances-related debacle that saw Celtic’s main rivals Rangers relegated to the Third Division.

2. Robin van Persie can do no wrong right now

(Manchester United’s Robin van Persie celebrates after scoring against Sporting Braga during their Champions League Group H match – Paulo Duarte/AP/Press Association Images)

The striker has not only met but exceeded the lofty expectations placed on his shoulders following his arrival at Old Trafford this summer.

He has grabbed some vital goals already this year, and such form has seen United justifiably placed as favourites to lift another Premier League trophy come the end of the season.

And against Sporting Braga last night, as has often been the case this season, Alex Ferguson’s men were sub-par, yet Van Persie still managed to shine.

With United losing 1-0, his belated introduction as a substitute changed the course of the game.

United proceeded to score three late goals, with the Dutchman proving highly influential, and grabbing the all-important equaliser.

3. Man City only have themselves to blame

(Manchester City manager Roberto Mancini complains to referee Peter Rasmussen after the final whistle – Martin Rickett/PA Wire/Press Association Images)

Roberto Mancini was visibly upset at what he perceived as the unfair treatment being handed out to his team, as they suffered another disappointing result in the Champions League at Eastlands.

And while he may have had a point with regard to one or two of the decisions against the hosts, he can have no real complaints in the general scheme of things.

For all the millions they’ve spent, City have invariably flattered to deceive in Europe, more often than not getting outplayed when up against technically superior sides such as Dortmund and Real Madrid.

And while they may have been somewhat unlucky against Ajax, Mancini’s men were highly fortunate to secure a draw against a far superior Dortmund side a few weeks ago.

Consequently, assuming City exit the Champions League at the first hurdle, they should assess their own failings, rather than doing their utmost to highlight unfavourable refereeing decisions.

4. Arsenal showing a distinct lack of confidence throughout the team

(Arsenal’s Olivier Giroud reacts after the Champions League group B match between FC Schalke 04 and Arsenal – Martin Meissner/AP/Press Association Images)

While Arsenal have at times shown signs of promise this season, their recent form has been inconsistent to say the least.

Having been outplayed against Man United at the weekend, they were again unconvincing away to Schalke in the Champions League.

While they will have drawn encouragement from taking a two-goal lead against the Germans, familiar failings quickly became apparent in the visitors’ game thereafter.

Their defence, with Steve Bould having previously been credited with its supposed vast improvement, was as shaky as ever, as Arsenal wilted following their excellent start.

Consequently, a lack of confidence seems to permeate the side at the moment, with even Santi Carzorla – the normally reliable midfielder who has arguably been Arsenal’s best player this season – showing signs that he too has been afflicted by this collective failure of morale, with the Spaniard’s slip-up leading directly to the first goal.

Such flaws, combined with their ostensible inability to find a credible replacement for Robin van Persie, suggest a troubling road ahead for Arsene Wenger and his men.

5. Chelsea’s skill is complemented by their oft-overlooked tenacity

(Chelsea’s Juan Mata and Shakhtar Donetsk’s Tomas Hubschman – Stephen Pond/EMPICS Sport)

Chelsea’s victory over an accomplished Shakhtar Donetsk outfit at Stamford Bridge was impressive for two reasons.

Of course, the immense technical skill displayed by footballers of seemingly limitless talent, such as Oscar and Juan Mata, was one admirable element of their win.

However, the most surprising and arguably more impressive quality they demonstrated was the perseverance evident in their overcoming the persistent setbacks prompted by Shakhtar’s clear unwillingness to give up easily.

The hosts continued to play in a positive fashion, despite their opponents equalising twice through the brilliant Brazilian Willian.

And what’s also telling is that this performance came in the wake of their most unsettling period of the season so far, having gained just one point from their past two Premier League matches.

In recent days, critics have questioned Chelsea’s capacity to last the distance both domestically and in Europe.

If last night’s evidence was anything to go by, they’ll surely relish the challenge.