Following Mourinho's recent statement and team selection against Ajax, it looks as though Lass, Alonso, and Khedira will be starting in midfield against Barcelona.
With Ronaldo, Benzema, and Di María as the attacking trivote, it will most likely be 4-3-3 for Real Madrid this Saturday.
The key player who will miss out against Barca is playmaker Mesut Özil.
The German has been a regular starter since his move from Werder Bremen in 2010, but he is not the right fit for this tactical system.
Özil does not provide the defensive work-rate or high pressure to play opposite Ronaldo or alongside Alonso in midfield.
If Arbeloa is fit for Saturday, Alonso will be joined by Lass and Khedira in midfield. The Spaniard will be responsible for finding the quick outlet pass, and launching the counter-attacks.
Lass and Khedira will provide great energy in midfield, as they look to break up Barcelona's possession game and tiki-taka style of play.
With this three-man midfield, Khedira will most likely be given the most freedom to get forward in support of the attack.
Lass will assume Pepe's role as the midfield enforcer, marking Messi through midfield and closing down opponents quickly. Khedira's tactical awareness will be important, but Lass has the quickness and tenacity to play a major role on Saturday.
Although this 4-3-3 will not produce four goals and attractive football, it is a winning formula against Barcelona.
Mourinho will set out with his team pressing high and trying to force mistakes at the back. With Lass, Khedira and Alonso and midfield, it will be difficult for Barcelona's little maestros to find passing lanes in the final third.
Saturday will be a significant test for Mourinho's men and this 4-3-3 formation.
Barcelona have been the best club team in the world in recent seasons.
However, Real Madrid are in fine form and they will be looking to make a statement against the reigning Spanish and European champions.