The injury provides a major blow to NYCFC's Audi 2023 MLS Cup Playoff aspirations after they brought the Argentine No. 10 back in early August. Upon leaving Argentine top-flight side Racing Club, he signed through the 2024 MLS season.
Moralez, 36, played in four games (all starts) this season, providing the creative spark NYCFC needed from the MLS Cup winner's previous stint (2017-22) at the club. During that initial period, he tallied 26 goals and 69 assists in 162 regular-season games.
"Maxi has made an immediate impact on the team since he returned, and we are deeply disappointed to lose a player of his caliber this late in the season as we push for the playoffs," NYCFC sporting director David Lee said in a release.
"We all know what Maxi means to NYCFC and our fans, his presence will be missed both on-and-off the field. We will give Maxi all the support needed throughout his recovery to help him return as soon, and safely, as possible."
As Moralez undergoes surgery and recovers, NYCFC sit 12th in the Eastern Conference table (30 points; 6W-10L-12D record) with six games remaining. They are three points below the playoff line, in danger of their first postseason-less season since 2015 (expansion year).