Iniesta
Iniesta suffered a minor calf injury during the weekend's 2-2 draw against Celta Vigo. Getty

Andres Iniesta, Javier Mascherano, Ousmane Dembele and Rafinha Alcantara took part in Barcelona's training session on Friday morning (8 December) with the La Liga leaders preparing for Sunday's trip to Villarreal.

The news is a major boost for Ernesto Valverde ahead of a crucial month which will include the first El Clasico of the season at Real Madrid on 23 December.

Dembele, Rafinha and Mascherano are still expected to miss the upcoming clash with Villarreal however while it is still uncertain whether the Barcelona captain will be 100% fit to feature on Sunday.

Iniesta missed the 2-0 victory over Sporting CP in the Champions League on Wednesday night (6 December) after suffering a minor calf injury during the weekend's 2-2 draw against Celta Vigo.

However, the 33-year-old stepped up his recovery on Friday morning and will still have another workout on Saturday to prove his fitness before the clash with Villarreal.

Meanwhile, Mascherano has been out of action since suffering a hamstring injury on international duty with Argentina on 14 November.

Barcelona suggested at the time the centre-back won't be available until the La Liga clash with Deportivo La Coruna on 17 December after ruling him for around four weeks.

The former Liverpool defender could be ready to return to action in the coming days but, if the original diagnosis was correct, the game with Villarreal would still come a little bit early for him.

Dembele and Rafinha will definitely miss the clash with the Yellow Sumbmarine but the news from Friday's workout will surely be welcomed by Valverde.

The France starlet was expected to be out until next year after he suffered a serious hamstring injury which required surgery during the Catalans' 2-1 victory over Getafe on 16 September.

However, the club record signing completed part of a training session with the rest of his teammates on Wednesday and there are suggestions that he could be back in time to face Real Madrid on 23 December.

Rafinha's recovery has been even tougher with the Brazilian having undergone two different operations since suffering a knee injury eight months ago.

Valverde will therefore be especially cautious with the midfielder but his return to training suggests that it won't take long before he is back in action again.

The Barcelona boss also promoted centre-back David Costas from the second team to the training session with Samuel Umtiti expected to be on the sidelines until February due to a hamstring injury sustained during the last weekend's draw against Celta.

The 22-year-old defender could have a chance to make the squad against Villarreal to back-up Gerard Pique and Thomas Vermaelen unless Mascherano makes a quick recovery.

"Back to work at the Ciutat Esportiva with Andrés Iniesta, Javier Mascherano, Ousmane Dembélé and Rafinha all completing part of the session with the rest of the squad. Training on Friday also saw Barça B defender David Costas take part," the club confirmed.

"The session served as continued preparation for Sunday's game against Villarreal (8.45pm CET) in week 15 of La Liga. Rafinha's return was the big news of the day and he was welcomed back in traditional style buy his team mates. The Brazilian trained for part of the session with the rest of the squad for the first team since injuring his right knee in April of last season away at Granada."

Barcelona have dropped points in their last two La Liga games against Valencia and Celta but still remain at the top of the table, five points ahead of Los Che and eight over Real Madrid, who are fourth behind Atletico Madrid.