Bayern Munich defender David Alaba was due to undergo surgery on Tuesday after suffering a stress fracture to his left foot in a friendly match against Napoli.
The 20-year-old Austria international is expected to be sidelined for between six and eight weeks and will miss the start of the Bundesliga season.
The club decided on the operation after a further examination of the injury on Monday.
Fellow defender Rafinha, who suffered a torn ankle ligament injury in the 3-2 defeat to Napoli, will not need surgery, the club said.
The Brazilian, however, will also miss the start of the season.
Eintracht Frankfurt goalkeeper Oka Nikolov will end a 19-year association with the Bundesliga club to continue his career in Major League Soccer.