By contrast, Rayo are languishing in 16th place with just a solitary win to their name this season, and a crushing 5-0 defeat at Malaga in their last match will have done nothing for the confidence of Paco Jemez's side.
After also conceding five against Atletico Madrid, Jemez will surely be hoping that Barca don't bring the swagger and confidence of their 7-0 demolition of Levante to the party, a team Rayo have already lost to this season incidentally.
Gerardo Martino has one enforced change to deal with after Jordi Alba was ruled out for three weeks with a hamstring injury, per Daily Mail. However, in Adriano Correia they have a ready-made replacement.
Given that Rayo have only scored four goals in their four La Liga fixtures this season, it would surely be an opportune time to blood Marc Bartra in the centre of defence, whilst also giving Gerard Pique a rest and some food for thought.
During the summer, B/R's Tre' Atkinson identified a few areas where Pique needed to improve, yet he has already demonstrated this season that there is still much work to be done. Think of his positioning for Helder Postiga's second goal for Valencia by way of example.
A short spell on the bench may be just the kick up the backside that the Catalan needs to help rediscover his best form.
Javier Mascherano and Dani Alves are "shoo-ins" for the other two defensive spots.
Alex Song could certainly do a job in place of the reliable Sergio Busquets in the holding role, whilst Cesc Fabregas or even Jonathan Dos Santos can slot in for either Xavi Hernandez or Andres Iniesta.
Much depends on Martino's school of thought.
Whether he intends to adopt the same policy as his predecessor Tito Vilanova—and play his strongest squad from the start of every game but risk alienating certain members of the playing staff—or in games that look eminently winnable, to allow senior players to recharge the batteries.
Rayo are a team shorn of confidence having conceded 12 goals in their four matches so far, and despite Jemez's backing, per Football Espana, they are ripe for the picking. Don't be surprised therefore to see Dos Santos get a rare starting opportunity.
The Brazilian needs games and with each passing 90 minutes, we are beginning to see the shoots of a reasonable partnership developing with Messi.
Once he gets out of the habit of feeling the need to pass to the Argentine at every given opportunity, then we should see the same Neymar that we habitually witness devouring defences for the Canarinho.
Messi himself just can't stop scoring again this season, and there should be rich pickings available for him in this match.
The right-sided berth is wide open once more. Cristian Tello didn't really do enough in his one hour cameo against Sevilla to justify his inclusion, therefore it's a straight fight between Alexis Sanchez and Pedro Rodriguez.
Sanchez shows more industry in general terms but it's Pedro that offers the greater goal threat, and for this reason he gets the nod.
Football can throw up some intriguing results at times, but it would be a huge shock if Barca were to succumb at Vallecas.