Champions Barcelona visit Rayo Vallecano in La Liga on Saturday reeling after midfield Gavi's devastating cruciate ligament injury, which is set to rule him out for the rest of the season.

Coach Xavi Hernandez has called the 19-year-old the "soul" of the team on multiple occasions and his tenacity will be badly missed with the Catalans already struggling for form.

The trip to Rayo's Vallecas stadium starts a tough run of fixtures for third-placed Barca, four points behind leaders Girona at the top of La Liga.

Barca host Porto on Tuesday looking to claim Champions League last 16 qualification, before welcoming Atletico Madrid and then Girona in key domestic clashes.

"It's an unfortunate injury, the important thing is he recovers because Gavi has a big present and an even bigger future," Barca president Joan Laporta said on Thursday.

"The club is by his side for whatever is necessary."

Sporting director Deco said Barcelona could not find a substitute for the midfielder in the winter transfer window.

"We're really sad about Gavi's injury, I've said ... that I think that Gavi is irreplacable," he explained.

"We won't find any player like him and so that's why it's not so easy."

Barcelona have been ravaged by injuries in recent weeks but Gavi's issue is the most severe and a big absence for the club to manage in terms of intensity and pressing.

Gavi was suspended for Barca's last match before the international break, a fortunate 2-1 home win over Alaves, and the team badly missed him, turning offering an insipid display.

Frenkie de Jong returned to training this week and may be ready to play after an ankle sprain has kept him out since mid-September, but goalkeeper Marc-Andre ter Stegen is a doubt.

Barcelona will need the Dutchman, summer arrival from Manchester City Ilkay Gundogan and Pedri, freshly back from an injury layoff himself to step up and muster up at least some of the energy Gavi offers.

Francisco's Rayo Vallecano can be a tough nut to crack, as Real Madrid found in a frustrating 0-0 draw against their city rivals earlier in November.

Rayo also came close to taking points off surprise package Girona but fell to a 2-1 defeat by Michel's shock leaders.

Girona host Athletic Bilbao on Monday, looking to at least preserve their two-point lead on second-place Real Madrid.

Carlo Ancelotti's side, also beset by injuries, visit Cadiz on Sunday.

Real Madrid were dealt bad blows by Eduardo Camavinga's own knee ligament tear while with France, joining long-term absentees Thibaut Courtois and Eder Militao, and Vinicius Junior's hamstring injury.

With Spain's top two suffering, Girona and Atletico Madrid, fourth, will look to pile on the pressure.