Watford will be without Ismaila Sarr, Ben Foster and Nicolas Nkoulou for at least a month because of injury.
Senegal winger Sarr has a knee ligament injury which the club say will be scanned again in about a month.
The Hornets added that keeper Foster has been "nursing a groin strain in recent games" and "will be out of action until January".
Cameroon defender Nkoulou has a hamstring injury which means he is sidelined "until into the new year".
Sarr went off after 68 minutes of the 4-1 win over Manchester United on 20 November and missed the subsequent 4-2 defeat at Leicester City.
The injury puts his participation with Senegal at the Africa Cup of Nations, which begins on 9 January, in doubt.
Nkoulou suffered his injury against United and, along with Sarr and Foster, was also out for the defeat by the Foxes.
Watford, who are 16th in the Premier League and four points above the relegation zone, host top-flight leaders Chelsea on Wednesday.
Claudio Ranieri's side then have a home game against Premier League champions Manchester City on Saturday.
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