Captain Moussa Sissoko will miss both tomorrow’s game at Portsmouth and the trip to Blackburn Rovers next Saturday.
The Frenchman was dismissed following his two yellow cards in quick succession against Burnley on Friday.
That would normally lead to a one-game ban, but because Sissoko has already received a red card this season he has to miss two games.
His previous dismissal was given to him retrospectively after the win over Blackburn Rovers in October.
Although not shown a card during the game, Sissoko was reported to referee Darren England by Blackburn skipper Lewis Travis during the first half for an alleged head-butt.
The match officials did not see the incident and so Mr England could not include it directly in his match report, but he referenced what Travis had told him in the section which allows referees to supply any additional information.
The FA then studied video of the alleged incident, which was understood to show Sissoko - who denied the charge - pushing his head towards Travis.
As a result, the FA retrospectively handed Sissoko a three-match ban – the same as he would have received had Mr England seen it and shown a red card for violent conduct.
Edo Kayembe, who was also sent off against the Clarets for two yellow cards, will only miss the Portsmouth game due to the usual one-match suspension.
Central defender Kevin Keben is once again in contention to make his first appearance for Watford since February 23.
The Cameroonian has been beset with injuries since signing from Toulouse in the summer and has played only 154 minutes.
Young forward Zavier Massiah-Edwards is also available again after completing a spell on the sidelines due to concussion protocols.
The teenager took a blow to the head when he came on as a substitute in the recent win over Hull City and therefore had to sit out the games against West Brom and Burnley.
Kwadwo Baah, Giorgi Chakvetadze, Yasser Larouci, Angelo Ogbonna and Amin Nabizada are all expected to miss the remainder of the season.
