So much of what Barcelona does is about style and grace and sporting beauty, it is easy to forget there is another crucial element that great champions sometimes need:
Barca might have used up its full allotment of fortune for the year on Tuesday night, treading a tricky path through soccer fate to survive a scare and clamber past Arsenal into the Champions League quarterfinals.
This was a night when the best club team in the world and the overwhelming favorite to win the trophy could have found itself dumped out of the competition. Instead, one key Arsenal mistake and a glaring refereeing error was all it took for Barca to capitalize and keep on marching.
The turning point of this round-of-16 second leg came in the second half, when Arsenal striker Robin van Persie was issued a red card that will be discussed countless times between now and the end of the season.
Gunners boss Arsene Wenger is never one to keep quiet about perceived injustice, and he was livid at van Persie being given a second yellow card for kicking the ball away after being called offside. Indeed, the decision from Swiss referee Massimo Busacca did seem overly harsh, especially given that van Persie could barely have been expected to hear the whistle above the raucous din from the Nou Camp stands.
Wenger berated Busacca at the final whistle, while van Persie seethed to journalists. "How am I supposed to hear the whistle when there are 95,000 jumping up and down and screaming?" said the Dutchman. "I couldn't hear a thing.
"I think the sending off was a total joke. There was only one second from his whistle to my shot and it is a joke. I explained it to him but he was bad all evening."
By the time van Persie was given his walking papers, the game had developed into a thriller. Barca had already received a couple of slices of luck in the first half, firstly when Arsenal goalkeeper Wojciech Szczesny had to leave the field with a damaged finger and critically when Gunners captain Cesc Fabregas uncharacteristically gave the ball away and allowed Lionel Messi to score just before the break.
However, a mistake from Sergio Busquets, filling in for the injured Carles Puyol at the heart of the Barca defense, had allowed Arsenal to go level and ahead on aggregate score. Busquets, who normally operates in midfield, rose to head clear a corner after 53 minutes but mistimed his jump and could only steer the ball into his own net.
At that point Arsenal, which had won the first leg 2-1 at the Emirates Stadium two weeks ago, fancied its chances of holding on to record a famous triumph. Yet just two minutes later, van Persie was ordered from the field and gave Barca the kind of man advantage that it relishes.
A calmly taken finish from Xavi and a penalty from Messi with 19 minutes to go were enough to put the Catalan giants through and avoid another night of European frustration.
While Pep Guardiola's Barca has been widely considered the greatest team on the planet for the past few years, it was denied at the semifinal stage by Inter Milan last year, a frustrating experience that still rankles.
"We know that when you get to this point of the competition there are always dangers," said head coach Guardiola. "We were not perfect, but we have got the result. We have come through and that is what is important."
The two somewhat muted performances against Arsenal were surprising if only because Barca usually looks so unstoppable, having won 24 of its 27 Spanish league games this season. The passing game Guardiola demands is implemented like clockwork each week and orchestrated by the brilliance of Messi, Xavi and Andres Iniesta.
Yet one has to suspect that Barcelona's European rivals won't take too much solace in the apparent fallibility displayed vs. the Gunners. Indeed, after experiencing a blip like this, it is hard to see them having another one.
Luck might have played its part, but Barca's Champions League campaign is very much on track.