Rotherham boss Paul Warne will be absent from his side's Sky Bet Championship games against Watford and Bristol City after entering a period of self-isolation.
The Millers are set to return to action on Tuesday after being forced to postpone their last three games due to a coronavirus outbreak at the club.
But Warne and first team coach Matt Hamshaw are among those still forced to stay away, leaving assistant manager Richie Barker and goalkeeping coach Andy Warrington to take charge against the Hornets.
Warne said: "We have been hit really, really hard this time. It has gone through the camp and we've had a significant number of people self-isolating, including myself now.
"Richie will be able to take a session with the lads on Tuesday morning to take them through some work to prepare them as well as we can technically."
The Millers, who were also forced to postpone two matches following an initial outbreak in December, were able to reopen their Roundwood training base on Monday.
