Addressing reporters, Baker said the club's designated hitter will have a partial tear of his patellar tendon repaired.
Yordan Alvarez surgery scheduled to repair partial tear of his patellar tendon. Out for the year, per #Astros Dusty Baker. Brutal blow.— Greg Bailey (@GregBailey13) August 19, 2020
Earlier in the day, the Astros manager indicated his second year slugger could be out of the pandemic-shortened 2020 season.
"Yordan Alvarez, it looks like he's done, maybe for the year," Baker told Houston's SportsTalk790.
Alvarez had been placed on the injured list Tuesday, just a few days after making his season debut.
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He had an MRI on Monday after experiencing discomfort in his right knee. He had missed two games because of the injury.
Alvarez made his season debut Friday after being activated from the injured list and was hitting .250 with a home run and four RBIs in two games.
He had been on the IL because of a positive COVID-19 test before summer camp.
Alvarez, 23, batted .313 with 27 home runs and 78 RBIs last season en route to Rookie of the Year honors.
ESPN and The Associated Press contributed to this report.