Can Wenger fill the gap?
Arsene Wenger's managerial cv is scarred by the absence of a European trophy - and he admits the failure to win the Champions League also represents a gap in Arsenal's rich history.
So it will be with a sense of personal and professional mission that Wenger sends Arsenal out to face Manchester United in the Champions League semi-final second leg at The Emirates on Tuesday.
Failure to overturn United's 1-0 lead, an advantage which should have been more given Arsenal's obvious inferiority at Old Trafford, will make it four years without silverware for Wenger, a statistic that was unthinkable when the FA Cup was won against these same opponents in 2005.
One thing that has not altered since that day in Cardiff has been Wenger's iron-clad belief in Arsenal's players - and it was on show again at Old Trafford last week when we saw him in buoyant and bullish mood after an uncharacteristically timid loss.
Wenger assured Europe's media that we would see a different Arsenal on home turf - now we will discover if will be proved right or if it was a game of bluff and bravado designed to lift his beaten players.
Wenger has faced doubters before and prevailed - Manchester United were the opponents when Arsenal backed their manager's words with actions in a thrilling win at The Emirates in November.
And it is performances of that quality that presumably made Wenger so confident Arsenal will emerge victorious against United - even inviting one questioning journalist to his post-match news conference on Tuesday, where he would presumably be delighted to chew that fat with him about a landmark victory.
It will, however, take a mirroring of their manager's utter conviction if Arsenal are to achieve the double target of not only scoring against United, but guarding against the away goal that could see Wenger retain his status as one of the greatest coaches never to win a European crown.
Andrey Arshavin is ineligible, so much responsibility will fall on the creative forces of Cesc Fabregas, Samir Nasri, Emmanuel Adebayor and, if fit, Robin van Persie.
But it is Arsenal's weakened defence that will pose the greatest threat to their ambitions. Simple maths says one goal for United means Arsenal will need three - and they did not resemble a team who could achieve that against Sir Alex Ferguson's team at any point in the first meeting.
This did not shake Wenger's spirit or optimism in the moments following that loss, and he will be hoping to transmit that to his players.
United boss Ferguson was a mixture of delight and disappointment as he followed Wenger into Old Trafford's media suite, the pleasure of not conceding a goal shielding him slightly from the pain of knowing a three-goal victory margin would have been a more realistic measure of his team's supremacy.
Ferguson has other concerns, with Wayne Rooney, Carlos Tevez and Patrice Evra one yellow card away from missing a potential final meeting with Chelsea or Barcelona in Rome later this month.
Rio Ferdinand's return alongside Nemanja Vidic will give Ferguson added re-assurance - but Wenger will see this as a day of destiny for Arsenal and the opportunity to move a step closer to filling that space in his and the great north London club's trophy collection.
Over at Stamford Bridge, the clash of cultures between Chelsea and Barcelona continues with a second leg that is too close to call after a contentious first game in the Nou Camp.
What is certain - despite the bleatings of Barcelona - is that Chelsea coach Guus Hiddink once again tailored his tactics to suit the occasion and only Didier Drogba's failure to take a presentable first-half chance stopped them just short of perfection.
Hiddink's cautious approach was vindicated by Barcelona's subsequent slicing up of a Real Madrid side that was effectively forced to go on the offensive at The Bernabeu. The Dutch coach is too wise to try and please the purists at the expense of pragmatism and the moans coming out of Catalonia had a hollow - and indeed familiar - ring.
He will now have to conjure up a tactical approach which will be delicately balanced between attacking intent and caution, with Barcelona a huge threat, despite their recent Champions League disappointments against Premier League opposition.
Chelsea hold the slightest of advantages, but having shown they can hold Barcelona they must now demonstrate they can beat them - and the unjustified words of criticism aimed in the direction of Stamford Bridge from the Nou Camp will provide the perfect incentive.