Canterbury's preparations for their NRL sudden-death semi-final against the Sydney Roosters have been disrupted, with players reportedly quarantined from the rest of the team as a virus spreads through the Bulldogs.

According to Fairfax Media, at least two Canterbury players have been kept away from Belmore this week as they battle a virus.

It is understood one of the players had not trained all week while another was told to leave on Wednesday after also starting to show flu-like symptoms with a severe head cold.

The duo should play on Friday night at Allianz Stadium but remain in doubt.