There is no defencing the porous defences suddenly plaguing the domestic league winners, writes Ian Hawkey, as teams such as Manchester City and Real Madrid have suddenly sprung leaks.
No case for dubious defences in Champions League
Group D of the Champions League, more than any other, was always likely to be the focus of fascination in the early months of this season's competition.
Its ingredients? Four domestic champions, three former winners of the European Cup and, in the words of the Borussia Dortmund and Germany centre-half Mats Hummels, a collection of "the 10 best footballers of my generation".
He is 23, which makes him a close-enough contemporary of Madrid's Mesut Ozil, his Germany teammate, of Karim Benzema, Gonzalo Higuain and Angel di Maria, and of City's Sergio Aguero, Samir Nasri and Mario Balotelli.
There are footballers elsewhere, of course, who might reasonably claim a place in a list of top-10 talents between 22 and 25, but Hummels was making a point about how tough seems the pool in which, on Wednesday night, City host Dortmund and Madrid go to Ajax.
Group D, then, is full of deadly strikers.
But what Group D more surprisingly stands for in early autumn is the Group of Dubious Defending.
City had the best defence in England in 2011/12. That rigour has disappeared lately. Dortmund and Madrid were the Bundesliga and the Primera Liga's meanest travellers in 2011/12. Both have been strangely leaky since mid-August.
Apart from Juventus in Italy, in the major leagues of western Europe the standards of defending that earned domestic titles have not been maintained by defending champions.
France's Montpellier, who finished top of Ligue 1 last May with the stingiest rearguard in the land, kept their first clean sheet of the 2012/13 campaign only last weekend, in their eighth competitive fixture of the season.
Madrid have played nine competitive matches - in the Primera Liga, Spanish Super Cup and Champions League - this season and kept a clean sheet in only three of them.
They have dropped eight of their first possible 18 points and their coach Jose Mourinho, a man of workaholic tendencies in trying to anticipate an opponent's strengths and strategies, has been enraged by a series of errors by his players defending set pieces. He dropped Sergio Ramos, his vice-captain and the leader of the defence, two weeks ago.
Roberto Mancini, the City manager, has also been unhappy about the organisation, togetherness and anticipation of his defenders.
Mancini embarked on the campaign experimenting with a 3-5-2 formation, but has returned to the back four that served City successfully in 2011/12 to find the right balance.
Joleon Lescott's reputation grew in the first six months of the calendar year, with club and country.
Now Lescott is in and out of Mancini's XIs, none of which have been capable of going 90 minutes without conceding. City have let in 15 goals in nine matches in all competitions.
Dortmund, though buoyed by Saturday's 5-0 victory over Borussia Monchengladbach, take on City Wednesday night with concerns about recent lapses of their own.
A week ago, at Eintracht Frankfurt, they twice allowed a lead to collapse and ended up with a point from a 3-3 draw.
Jurgen Klopp, the coach was shown a red card late in the game. He was understandably vexed about how a squad who won the past two Bundesliga shields, having conceded a mere 47 goals in 68 games across two campaigns, had become so porous.
Hummels has come in for recent criticism in that regard. He is a defender who likes to move forward with the ball, a libero in instinct and a hugely accomplished footballer.
But some high-profile errors - one for Germany in their semi-final defeat to Italy at Euro 2012; a missed penalty against Ajax in the narrow 1-0 win for Dortmund on the opening night of Group D; and two slip-ups in the Eintracht Frankfurt game - have put him under scrutiny.
And as the player himself points out, there are plenty of strikers in devilish Group D ready to pounce on any insecurities felt by the likes of Hummels, Lescott or Ramos.
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