The champions have a game in-hand following their winter Club World Cup exploits.
Zinedine Zidane's men have a lot of ground to make up with their title defence seemingly in tatters already.
Three points would see them overtake Valencia and put them seven points behind rivals Atletico Madrid - but they would still be 14 points behind runaway leaders Barca.
With Cristiano Ronaldo set to be rested, will it be a happy night for Gareth Bale and Co?
The game is on Sky Sports Football and Sky/Now TV subscribers can live stream via their respective apps.
Watch Live HD TV: Click Here
And you can, of course, follow ALL the action right here at Mirror Football.
Leganes XI: Cuéllar; Tito, Siovas, Bustinza, Diego Rico; Gabriel, Gumbau, Eraso; Omar Ramos, Beauvue, El Zhar.
Real Madrid XI: Casilla; Carvajal, Ramos, Varane, Theo; Casemiro, Kovacic; Vazquez, Isco, Asensio; Benzema