I feel like it is really difficult to see Real Madrid gaining with Barcelona too much to take the lead from them and win the league title.
Because Barcelona are still able to keep the gap between them quite balanced. I don't think they would maintain a very bad form in the league while their main focus is on there already. After a break of a few years in the league Barcelona finally have a big chance to become the champions. They wouldn't gave it away easily. Their simple mistakes are happening less often than Real Madrid during the season.
Barcelona will not give out their opportunity of becoming the La Liga champions once again.
If they would want to do it is not at this time that they are already close to Success.
The major factor that can make Barcelona to lose the title race to Real Madrid is injury.
But looking at the current squad of Barcelona, you will understand that almost all the players are available.
This will rather make it difficult for Real Madrid to penetrate.
Real Madrid should simply taking the Champions League and forget about the La Liga which Xavi has worked for
And this season the opportunity for Barcelona to win the title is very wide open. because the focus of Real Madrid is being diverted by the match in the champions league. because it seems true that Real Madrid is currently more focused on success in the Champions League. and while Barcelona is currently only focused on winning the title in Laliga. Tomorrow Barcelona will play against Valencia. and I'm sure Barcelona will get full points back from this fight. and will further strengthen their position at the top of the standings.
Well, about the availability of players, Docnaster said that almost all the players are available, but look at the last Clásico, when top players, Lewandowski included, weren't available. It seems that their absence wasn't decisive, though, as they still managed to win the match.
About La Liga, FC Barcelona won't let Real Madrid win. At this point, they risk to concede not only this championship but the Club World Cup + Copa del Rey + (worse) Champions League. Fortunately, Barça already won the Supercopa, so it is impossible for Real Madrid to win all championships.