Henry's heroics hide the faultlines

Champions' League: Striker is magnificent, but Arsenal's unusually imperfect back four need protection

In a week when David Dein emphasised his aversion to his French players travelling to Australia for next month's friendly international there must have been times at Highbury on Wednesday night when the Arsenal vice-chairman considered banishing the entire Arsenal team to the former penal colony.

The collective exhalation of breath when referee Dick Jol's final whistle signalled Arsenal's progress to phase two of the Champions League came dangerously close to doing the demolition men's job for them and wrenching the famous old stadium from its foundations well ahead of the proposed move. The expression of relief was palpable, not least from Dein and his confederates, those balance sheet-fixated individuals responsible for the Gunners' long-term future.

The tension was severe enough for the Highbury faithful, whose emotions were put through the mangle. One can only imagine what failure to reach even the second phase would have done to the health of those in the boardroom. The fall-out wouldn't have necessarily been just financial, either. Would Arsène Wenger have ever got round to signing that contract? And what of Vieira's future?

For too much of Wednesday night's Champions League game, or rather until a splendidly poised Thierry Henry satisfied the desperate exhortations for a victory by the two-goal margin necessary to ensure qualification, Wenger's players too frequently betrayed themselves as a team whose domestic and European ambitions will continue to be prey to the brave and tenacious, if less naturally equipped predator. Like their fellow "big beasts" of the Premiership, Manchester United, theyattack with speed and savagery, but are prone to obligingly expose their underbellies to the fangs of rivals, as Blackburn and Real Mallorca have discovered in recent days.

The Gunners, once possessors of the most miserly, most disciplined rearguard in the country, now boast not so much a back-line as a faultline. In 14 matches this season they have shut out the opposition on only four occasions, and not at all in Europe. History advises us, as Leeds are confirming, and to a certain extent, Liverpool, too, that defences need to be settled and thoroughly familiar with each other's idiosyncrasies. Too much rotation and players get in a spin.

True, Tony Adams, the central defensive totem, is absent again through injury, as has been Ashley Cole in the last two games. Yet you wonder whether Wenger's decisions to give Sol Campbell some R&R, relegate Martin Keown, and draft in Matthew Upson, before, on Wednesday, deploying the two England internationals together, will have enhanced defensive harmony. Quite possibly not.

Wenger would argue that he "rested" Campbell against Blackburn to ensure his freshness to face Mallorca. But defence, arguably more than any other area, calls for an almost intuitive understanding and that will only emerge from a player developing as constant a relationship with his defensive team-mates as injury and suspension will permit. Though Campbell grew in confidence and stature during the game, he has yet to attain that formidable peak of performance that he achieved, with the greater responsibility he accepted as captain, at White Hart Lane.

However, defensive fallibility is not purely the remit of defenders. Arsenal manifestly miss the presence of Emmanuel Petit, who together with Patrick Vieira, provided such an effective guard for the Arsenal back line in their time together. Evidence that Giovanni van Bronckhorst, Wenger's £8.5m summer acquisition from Rangers, can effectively fulfil that role – his preferred one – is steadily being produced by the Dutchman. Against Mallorca, he had to cover for Cole at left-back, where he plays for Holland, and apart from being a keen tackler he is an excellent exponent of the measured cross, as he exhibited when supplying Dennis Bergkamp for his headed goal.

But elements of his display, not least the quick-witted manner in which he released Henry into uncontested opposition territory for that third, and decisive, goal with a perceptive, swiftly taken free-kick, must commend him to his manager as the long-term midfield partner of Vieira (assuming, that the Frenchman's own Highbury future is long term). It has not been a facile transition from Scottish to English Premier League for the 26-year-old. "I came to Arsenal determined to achieve things and this is the first time I've been in the second round [of the Champions League]. It's great for me to compete against all the big teams of Europe," van Bronckhorst said. "Rangers are a fantastic club. But you're playing in Scotland and if you play there too long your development will stop. When I sensed that I wasn't going forward any more, I knew it was time for me to change direction."

However, the Dutchman, who played for his home city club, Feyenoord of Rotterdam, and RKC Waalwijk before joining Rangers, admitted: "It's been very busy for me in the last month, coming to a new club and finding a new house, and my wife had a baby boy three weeks ago. It's all been very hectic, but now everything is settled at home. The coach [Wenger] has been very patient, and told me I've been getting stronger and stronger."

It was Bergkamp who was instrumental in his countryman's move to north London, that association helping Arsenal beat Chelsea to van Bronckhorst's signature. Between them, they appeared to have secured the 2-0 lead that the Gunners required, until Mallorca breached the home defence. Yet, mystifyingly, rather than protect a scoreline which would have kept them in the competition the visitors surrendered possession, and space for Arsenal to profit from it. The fact that it was Henry who exploited it in added time had almost been inevitable from the moment that Sir Alex Ferguson had declared the previous night that Ruud van Nistelrooy was European's pre-eminent striker.

Much though van Bronckhorst admires his fellow Dutch "van" man, the midfielder recognises that Arsenal's prospects of advancing further into Europe depend on the scoring instincts of a player who has failed to score in only four of Arsenal's matches this season. "He's right there [with van Nistelrooy]," he said. "Thierry's been fantastic in the Premier League, and now in the Champions League. He's also scoring the most important goals. I always thought he is very quick, but since I've been here and seen him in training, I've realised that he's very technically gifted as well. Around the box, he can get a goal at any time."

You suspect he may need to continue to do so while Wenger constructs a rearguard endowed with anything like the resilience of Highbury's famous four.