Who could have imagined that a Champions League group-stage week would be so much trouble for English clubs?

Far from being a walk in the park, Manchester City were soundly outplayed in losing to unheralded Russian opposition, Liverpool seemed to have given up against Real Madrid, while even stalwart Chelsea ­labored to a draw against a team from Slovenia.

However, the most eye-catching setback might have been Arsenal's. The Gunners were cruising at 3-0 up in the second half against Anderlecht, when the Belgian team ­suddenly scored in the 61st minute. Then they scored again 12 minutes later, and ­completed the stirring comeback in the 90th minute with a great headed strike from a cross.

Arsenal manager Arsene Wenger was so upset that the normally courteous Frenchman stalked down the tunnel at the final whistle without ­exchanging the customary handshake with the opposing manager.

Arsenal's defensive weaknesses have been known for some time, but this comeback by a much less talented team on a stage like the Champions League is a new low. It illustrates two things - a defensive weakness and a tactical naivete in not being to adjust to circumstances.

At 3-0 up, Arsenal continued to go on the offensive rather than tighten up defensively. And when Anderlecht scored and started to press forward for more, Arsenal were unable to shut things down. Even Anderlecht's manager was surprised by how open Arsenal were, as he told reporters that maybe ­Arsenal were overconfident.

On Sunday, returning to the Premiership wasn't any ­better, but worse as Arsenal lost to Swansea after going one goal up. Arsenal again failed to clamp down defensively to protect their lead and while Swansea's first goal was a great free kick, poor defending in the form of a defensive mismatch allowed Swansea to score the second.

Arsenal have an embarrassment of attacking riches, including Alexis Sanchez, Danny Welbeck, Aaron Ramsey, and Mesut Ozil. But in defense, they lack centerbacks and they have just one decent defensive midfielder.

Wenger and the club management should be blamed for this lack of balance. While two of their main signings in the summer were defenders, Wenger has always gone after offensive players, especially midfielders, in preceding years.

The next signing period for new players is in January, so Arsenal will just have to suffer with their defensive frailties for at least another two months.

The author is an editor with the Global Times. hiltonyip@globaltimes.com.cn