Andres Iniesta and Jeremy Mathieu will miss the second leg of the Supercopa de Espana and the start of Barcelona's LaLiga campaign through injury.
The pair had to be substituted in the first half of Saturday's 2-0 Supercopa first-leg victory over Sevilla at the Ramon Sanchez Pizjuan.
Lucas Digne replaced Mathieu in the 27th minute before Iniesta was withdrawn for Denis Suarez nine minutes before half-time following a collision with Mariano.
A strain to the right knee is expected to keep the Spain international out for two weeks, while his team-mate is facing a further seven days on the sidelines with a hamstring issue.
A Barca statement read: "This morning [Monday], after the tests have been done, the club's medical services have reported the exact extent of the injuries of both players.
"In the case of Iniesta, the report confirms a strain in his right knee. The estimated downtime will be two weeks, although the evolution will determine his availability.
"For his part, Mathieu has a distal tear in the right hamstring. The estimated downtime will be around three weeks."
Barca host Sevilla in the second leg of the Supercopa on Wednesday before starting their LaLiga title defence against Real Betis on Saturday.