MADRID, Jan. 6 (Xinhua) -- Both league leaders, FC Barcelona and Real Madrid return to Liga Santander action on Sunday with game at home to Levante and away to Celta Vigo.

It is the first league game for both sides since Barca won 3-0 in the Santiago Bernabeu before Christmas. That win put Barca 14 points ahead of Madrid, all be it with an extra game played, and that gap could momentarily at least have opened to 17 points if Barca are able to defeat Levante on Sunday afternoon.

Barca coach Ernesto Valverde rested Andres Iniesta, Leo Messi, Jordi Alba and Luis Suarez for the 1-1 draw in the King's Cup away to Celta on Thursday and all four will start against Levante.

Meanwhile Ousmane Dembele, who returned from over 3 months out injured when he came on as a second half substitute in Vigo can expect more game time, while Rafinha, Paco Alcacer and Arda Turan are unavailable through injury.

Levante have lost steam since a good start to the season, but have a good away record, as shown by their 2-1 Cup win against Espanyol on Thursday, while they haven't lost in their last five league matches away from home, keeping three clean sheets in the process.

Whatever Barca's result, Real Madrid go into their game in Vigo knowing nothing other than a win is any good for their title ambitions, but Zinedine Zidane's side also need to improve their football as well as their results.

Two penalties helped them to a Cup win away to second division Numancia on Thursday, but their performance was again below par and at times they struggled against a rival reduced to 10 men.

Players such as Ronaldo, Luka Modric and Tony Kroos will be back in Vigo, while Gareth Bale will probably partner Ronaldo in attack.

Celta drew 1-1 at home to Barca in the Cup and took a 2-2 draw from the Camp Nou earlier this campaign and pacey strikers Iago Aspas and Pione Sisto, as well as the powerful Maxi Gomez will be a handful for a Madrid defense missing the suspended Dani Carvajal and the injured Sergio Ramos.?