Crocked Carrizo out for three months
Carrizo, who had spells in Europe with Lazio and Real Zaragoza after helping River win their record 33rd league title in 2008, fell badly going for a cross during a practice at the Atlantic seaside resort of Mar del Plata.
"He has a ligament injury of the left ankle. We're going to operate on him to give him more stability and so he doesn't have problems in the future," team doctor Luis Seveso told reporters.
The 26-year-old has been capped 10 times by Argentina.
River lost 2-0 to arch-rivals Boca Juniors in a friendly last weekend that was part of traditional tournaments held every year during the season's summer recess. Stung by the defeat, he had talked of revenge but will miss the teams' clash in Mendoza next week.
The Clausura championship, second of the 2010/11 season, kicks off on February 11.
River finished fourth in the Apertura won by Estudiantes last month but they are dangerously close to relegation that is calculated on points obtained over three seasons.