The 26-year-old damaged his hamstring in Thursday night's 7-0 win over Malaga, a match in which he scored a hat-trick to take his goals tally for the season to 37.
He has appeared in every league game so far this season, with his goals helping his side retain a semblance of hope of reducing the seven-point gap between themselves and Barcelona.
But he now looks set to miss Sunday's game with Racing Santander and the subsequent meeting with Hercules, as well as the second-leg of Madrid's Champions League tie with Lyon, which is currently level at 1-1.
A statement on the club's official website read: "Cristiano Ronaldo has a Grade 1 muscle injury on the left biceps femoris muscle (hamstring). The player will miss 10-15 days. His recovery is being monitored."
The Portugal international, who left the pitch at his own request after scoring his third goal on Thursday night, could target the Madrid derby on March 19 to make his return.
