Thomas Vermaelen, Sergi Roberto step up as Barcelona's unexpected signings

After a particularly poor defensive display in the European Super Cup Final and a shoddy showing in the Spanish Supercopa, Barcelona posted a couple of unspectacular but unerring opening outings in La Liga before taking on one of the toughest tests of the season in the cauldron-esque atmosphere of the Vicente Calderón.

In by far the best performance of the season so far, the Blaugrana edged Atletico Madrid 2-1 at the final whistle thanks to a superb Neymar free kick and a winner by who else but Lionel Messi after finding themselves behind when Fernando Torres notched the opener on 51 minutes. Many positives can obviously be taken from dispatching a potential title rival, but all three inaugural games of the season have offered up plenty of reason for optimism (some of those falling under the 'pleasant surprises' category). 

In a summer when Barcelona couldn't strengthen their squad due to the controversial ban from FIFA, two unexpected players have stepped forward and excelled under the spotlight: Thomas Vermaelen and Sergi Roberto.

Thomas Vermaelen: Gerard Pique's new partner?

Following a season where Thomas Vermaelen only made one La Liga appearance in the last match of the year after his new club had clinched yet another title, Barcelona's centre-back pecking order was grim reading for the former Gunner. 

Although much of this was down to a sadly typically injury-filled season, the Belgian international must have been questioning whether half-heartedly celebrating his team's trophy victories from the sidelines would typify his career with the Catalan giants. 

This season, however, has been greatly different for him already, with Pique missing from action due to a suspension and Enrique's apparent mistrust in Marc Bartra and even Jérémy Mathieu, Mascherano has required a central defensive colleague. 

Step forward, Thomas Vermaelen. 

Since his inclusion, the Belgium international has provided more stability than any of the aspirants to take his spot and has even scored an immensely important winner against Málaga (a team that Barca were unable to score against last year). 

Unfortunately, injury has reared its ugly head again for Vermaelen as he was forced off in the Calderón. Fortunately, this latest setback isn't substantially serious (only three weeks, doctors expect) and he'll be pulling on a Blaugrana shirt again in the near future.

Sergi Roberto: A long term Dani Alves successor?

When Dani Alves went down wincing with a groin injury that prematurely ended his first game in the league in the San Mamés, nearly all Culés were wincing along with him. 

With new signing - and, by common consent, Alves' future replacement - Aleix Vidal unable to make a Barca appearance until January, Sergi Roberto was given his latest and possibly final chance to impress at the relatively alien position of right back. 

However, this time, Roberto's opportunity has not went begging. Transitioning from his more familiar central midfield role, he has utilised his attributes to perfectly suit that of a Barcelona wing back. His stamina and endeavour coupled with his ball playing ability obtained through beginning as a box-to-box midfielder has made him a perfect fit for the place he now occupies. 

In one of Luis Enrique's team's hardest positions, Sergi Roberto has excelled, and has given no cause to question when Alves will be fit again due to the Brazilian being missed. 

Solid defensively in all three matches, matching Alba's intensity on the opposite flank and the ability to link up with Suárez, Rakitić and Messi have made the La Masia graduate one of the shining lights in Barca's first few fixtures.

By Joel Boyd, columnist at Barcablog. Follow him on Twitter @JoelBoyd10.

Now, It's Your Turn

Do you expect Sergi Roberto to keep his place after Dani Alves becomes fully fit? Will this latest injury destroy Vermaelen's hopes at Barcelona once and for all?