Sri Lanka's team were hit by a Covid-19 outbreak on the eve of Friday's second test against Australia with Dhananjaya de Silva, Jeffrey Vandersay and Asitha Fernando all testing positive for the virus.
"All three players were found to be positive during a Rapid Antigen Test conducted yesterday," Sri Lanka Cricket said Thursday.
The hosts are looking to bounce back after their crushing 10-wicket defeat inside three days in the opening test of the two-match series.
Angelo Mathews has returned to the team after testing positive during the first test but Praveen Jayawickrama had already been ruled out on Tuesday after testing positive for Covid.
Sri Lanka had already reinforced their spin bowling contingent with the addition of Maheesh Theekshana, Dinuth Wellalage and Prabath Jayasuriya along with all-rounder Lakshita Manasinghe, who bowls off-spin.
Lakshan Sandakan, a left-arm wrist spinner who last played a test in 2018, was Thursday added to the squad as further cover.