The Argentinian was substituted at half time of the 2-2 draw with Paris Saint-Germain in the Champions League quarter-final first leg on Tuesday.
The 45-year-old has confirmed that the four-time Ballon d'Or winner has been receiving specialist treatment over the last few days as he aims to return for the second leg of the tie at the Nou Camp on Wednesday.
Rouri - who took charge of the Catalan club for a large period of the season in the absence of boss Tito Villanova - believes it will be touch-and-go over the next week as they face a race against time.
Roura said: "It's difficult to say.
"We'll see what state he's in by Wednesday. For the game tomorrow, logically, his chances are low."