Glasgow Warriors' Pro14 meeting with Edinburgh on 27 December has been postponed after at least four positive Covid-19 tests in the Glasgow squad.
Warriors' European Champions Cup match against Lyon on Saturday had already been cancelled.
Twenty Glasgow players were forced to isolate after a coronavirus outbreak at last weekend's Champions Cup opponents Exeter Chiefs, who won 42-0.
Four Warriors players subsequently returned positive tests.
And the Scottish club are awaiting the results of a further round of testing.