After undergoing surgery on his right foot in Brazil over the weekend, the world-record signing was ruled out for the remainder of the European season.
It proved an untimely blow for the Ligue 1 leaders ahead of their second leg tie in the last-16 round with Los Blancos.
But Emery is confident Angel Di Maria can step in and provide a similar influence as the Brazil superstar - with Les Parisiens looking to overturn a 3-1 deficit.
"Angel is an important player who has the quality to make the difference," Emery told reporters ahead of Tuesday's clash, as quoted by Marca.
"He's got both the confidence and the desire. We want the players to be at their best level on Tuesday, and for some like Angel, it will be a special moment."
The 30-year-old Argentine has scored 16 goals and registered 15 assists in 32 games across all competitions this season.