River faces defensive difficulties ahead of their visit to Libertad: Rivero out and Paulo Díaz in doubt

The anterior cruciate ligament tear in the left knee that Germán Pezzella suffered in the draw against Independiente set off alarms at River. El Millonario will face the round of 16 of the Copa Libertadores against Libertad with a shortage of center backs and, to make matters worse, without Lautaro Rivero on the eligible list, even though the defender was recalled from Central Córdoba and made his debut against Rojo.

The absence of the world champion with the Argentina National Team adds to that of Lucas Martínez Quarta, who is suffering from a knee sprain and won't be available for the first leg. In addition, Paulo Díaz's chronic synovitis kept him out in Avellaneda and leaves him doubtful for the match in Paraguay.

Sebastián Boselli, who replaced Pezzella against Independiente, filled the only center back spot that River allocated on the list, while the other four changes were for Maximiliano Salas, Juan Fernando Quintero, Juan Carlos Portillo, and Matías Galarza. Although the club has until Monday at 6:00 p.m. to submit the final roster to CONMEBOL, it can't modify the provisional one submitted on Friday, in which Rivero doesn't appear.

Barring any surprises, the starting duo on Thursday at 9:30 p.m. at Defensores del Chaco will be Paulo Díaz-Boselli, a pairing not seen in Marcelo Gallardo's second spell. As an alternative, Juan Carlos Portillo could appear, a central midfielder with experience as a defender, who is recovering from quadriceps tendinitis.

The list also includes Federico Gattoni and Ulises Giménez, although the former is not considered by the coach and the latter has only played four minutes in the first team. Only an emergency would make Gallardo turn to them.