Barcelona captain Carles Puyol has been given the all-clear by medical staff and included in the squad for Saturday's game at Real Sociedad, the Spanish and European champions said on Friday.
The Spain international has not played since undergoing knee surgery in June and his return is a welcome development for coach Pep Guardiola, who is still missing Puyol's partner in central defence Gerard Pique.
"He is a fundamental player for us, he gives us things that others do not, he is the captain, he has proven experience in a wide range of situations," Guardiola told a news conference.
"Seeing him content and shouting in training makes us happy and stronger."
Barca have occasionally suffered a dip in form in recent seasons after their players returned from international duty and Guardiola said they are hoping to avoid a similar slip-up on Saturday.
"The first match back after internationals has always been tough for us.
"Real Sociedad are playing differently to last year and it's a team that has made a very good impression on me. We'll have to prepare ourselves well and make a big effort."
Full-backs Adriano and Maxwell and midfielder Ibrahim Afellay were also given the all-clear after injury and are available for the game in San Sebastian, Barca said in a statement on their website.
Sociedad beat Barca 2-1 at their Anoeta stadium last season and their Norway defender Vadim Demidov said the Basque club's strong form at home could surprise the Catalans.
"I think this year will be tougher because they are an incredible team but winning one match against them is not impossible because we are strong at the Anoeta," he told a news conference.
Real Madrid are a better team than last season and are capable of getting the better of Barcelona, Spanish champions for the past three years, according to Real's Portugal forward Cristiano Ronaldo.
"To beat them we have to play at 100 percent, but I also think that this season we are more competitive, more mature and have more experience," Ronaldo said in an interview published in Friday's Marca sports daily.
"That's why I think this will be Real Madrid's year," La Liga's top scorer last season with 40 goals added.
Real host city rivals Getafe on Saturday following a 6-0 demolition of Real Zaragoza in the first round of matches.
Getafe coach Luis Garcia, who joined from Levante at the end of last season, said on Thursday he was concerned about a number of injuries in defence and on the wings but insisted his side were capable of causing an upset.
"They have an excellent counterattack and also exploit the spaces very well," Garcia told a news conference. "But Barca and Madrid won't take all the points and there is always a chance."
Valencia can still have a good season despite the loss of Spain forward Juan Mata to Chelsea and the club proved they can survive the exit of top players after David Villa and David Silva left, coach Unai Emery said.
"I believe in this Valencia independently of who is here," Emery said in an interview in Friday's As newspaper ahead of his side's match at home to Atletico Madrid on Saturday.
"Last season we were able to improve on the previous campaign and overcome all the doubts, internal and external, that there were after we said goodbye to Villa and Silva."
Atletico's new signings including Colombia striker Radamel Falcao, Brazilian playmaker Diego and Turkey midfielder Arda Turan need time to adjust, coach Gregorio Manzano said at a news conference on Friday.
"Maybe some of the latest signings are lacking a little bit of connection with the rest of the team, which is logical," said Manzano, who is beginning a second stint with the club.
"It needs some time so that they can continue to adapt and improve their understanding with the others on the pitch."