EurosportReid was subbed off early in his side's resounding win over Gold Coast on Saturday night, with scans on Sunday confirming a partial tear of the medial ligament in his right knee.
The club expects the 20-year-old to be available for selection in 2-3 weeks, ruling him out of Sunday's match against Carlton at Etihad Stadium.
Reid is also in doubt for the Swans' blockbuster against the Magpies at ANZ Stadium on August 11, and an August 19 meeting with Western Bulldogs at Etihad Stadium.
"The good news is that the scan revealed no other damage to the knee and that no surgery will be required," Swans doctor Nathan Gibbs said in a statement.
