The 23-year-old picked up a muscle strain in last weekend's 3-1 win over Real Zaragoza, and is rumoured to miss out in Los Blancos visit to Getafe for Saturday's La Liga clash.
However, Garcia believes that former Benfica star Fabio Coentrao will fill in the gap that has been left behind by the Brazil international.
"If Marcelo is not available, then a guy who cost €30 million [Coentrao] will play." the former Levante coach told reporters.
The 39-year-old coach went on to rule out Dani Guiza from the match, and hopes the striker will live up to his reputation.
"Dani Guiza will not be able to play for us. I expect him to be important in the second half of the season."
Despite admitting the fact that Madrid are on their peak form, Garcia also insisted his squad were no slouches either.
"Madrid are the most in-form team by far, but they take on a strong Getafe, who have been playing very well and we hope it will stay this way," he added.
"This is our best moment, but I think the same can be said about Madrid. They were eliminated in the Copa del Rey despite having a spectacular match at Barcelona and they won their last two home matches easily."