As the teams lined up in the Nou Camp Thursday night, you would be forgiven for believing this was a testimonial being played for the enjoyment of a VIP rather than a crucial game between two of the top tipped teams in Group B of the Champions League. 

Lionel Messi, the undisputed star of Barcelona's lineup fractured his arm on Saturday and so watched from the sidelines – a fact the TV coverage believed to be so important that it dominated coverage; at least three different camera angles were deployed to make sure we could see him, arm in sling, with his son ready to watch the game.

Any other season and he would be worth all this attention. Messi is, after all, more than just a player for Barcelona. He embodies Barcelona's skill, ethos and tradition of victory. 

There is only one place where the world's best player can play and only one team that can facilitate the world's best player too. Normally, anyway. This year's La Liga season has been surprisingly competitive with the big two – Barcelona and their erstwhile rival Real Madrid – dropping points in unexpected places, such as a run of draws against Valencia, Athletic Bilbao and Girona; this lack of form has carried into Europe too. It's apt then, rather than a twist of fate, that Messi is injured: He is mortal, just like Barcelona.

Inter Milan, already riding high on seven straight wins including a last-gasp win in the Milan Derby last weekend, could smell blood on the pitch and were ready to play from the first whistle. 

A no-nonsense team with four at the back and a big lad up front, Inter treated Barcelona like they treat anybody else and started strong. Mauro Icardi had a convincing shot within the first 10 minutes and kept the ball high up the pitch, keeping goalkeeper Marc-Andre Ter Stegen on his toes.

But the map is not the territory, the narrative is not the facts. Messi may be Barcelona's key player, but without him, they are still Barcelona: 11 world class players including Luis Suarez, Philippe Coutinho and Rafinha. 

As soon as Inter lowered the pressure, Barcelona's possession play began, and like a magnetizing force, it took real strength for Inter to pull the ball back. 

If there was any sign on the pitch that Messi was missing, it's that the offense occasionally seemed aimless. Tiki-taka went on a touch too long without Messi there to slip through the classically Italian back wall.

That didn't stop Barcelona, however. It was goalkeeper Samir Handanovic who did that. If not for him, Inter would have shipped several over the next few minutes, starting with a cheeky header from just inside the box by Clement Lenglet, closely followed by two attempts by Rafinha; one poor, the other better but both clearly probing Luciano Spalletti's defense, and just on the other side of 30 minutes, the Brazilian gets what he's looking for. 

A gorgeously weighted cross out from the right by Suarez landed a handful of yards in front of goal, perfectly timed for Rafinha to catch it on the run and send it sailing into the net. Nobody could have stopped it.

Most teams would have caved in when faced with a goal that sublime, and Inter may have were it not for a good chance a few minutes later that came from Matias Vecino. The finish – a well struck, badly aimed volley – was irrelevant, it was the start – a run from Milan Skriniar - that revealed a chink in Barcelona's armor that Inter clearly thought they could capitalize on in the second half.

With one change that swapped midfielder Antonio Candreva for Matteo Politano, a young forward ready to assist Icardi up front, and a significant increase in the tempo, Inter came into the second half swinging. 

Five minutes in, Politano forced a save from Ten Stegen and then belted it into the sky minutes later. Both opportunities were wasted, but they were opportunities that weren't available at all in the latter stages of the first half and they came about simply by being more physical with the Spanish side.

It quickly became very clear that Barcelona aren't used to being manhandled and they regularly got their pockets picked. Again, this lead to Milan keeping the ball high and again they did nothing with it. 

It's with these missed chances that Barcelona showed just why they are one of the world's best; as they got slightly closer, they adapted their style and, almost out of nowhere, completely replaced their ball control style with open energetic play designed to make use of all the empty space in Inter's half.

The change of pace dazzled Inter. They could barely keep up. On the cusp of 70 minutes, they gave away a free kick to Suarez - who had been playing in desperation mode since flubbing his early chances - and, while he was setting up, Marcelo Brozovic creeped behind the line and lay down; Suarez thought he was clever going under rather than over the wall but got hilariously caught out instead.

Besides for this, Barcelona completely dominated the remaining twenty minutes and got their long-awaited second goal in the 83rd minute  when the pressure became too much for Inter, giving Jordi Alba a chance to burst through a gap in the defense and curl it past Ter Stegen, getting three points for his side and putting a big smile on Leo Messi's face in the process.

The talismanic number 10's presence may have been missing from the game itself, but in the end, Barcelona still managed to find out a convincing and much-needed win ahead of this weekend's domestic clash with Real Madrid. 

That game will be the first El Clasico without either Messi or Cristiano Ronaldo in over a decade and a win there will surely be a sign that Barcelona are getting back into their groove.