Swansea hope to have Darren Pratley available as they look to get their promotion charge back on track.
The midfielder failed to travel to Glanford Park for Saturday's 1-0 defeat to Scunthorpe having been struck down with a stomach bug ahead of the game, but manager Brendan Rodgers is optimistic he will return to contention against the Hornets.
Stand-in skipper Alan Tate was also struggling with the virus but played the entire 90 minutes on Saturday and will be in contention once again.
City are set to be boosted this week by the return to full training of captain Garry Monk (knee) and midfielder Andrea Orlandi (thigh) but they will not be match ready to play a part against Watford.
Forward Stephen Dobbie and striker Luke Moore are both pushing for recalls having been relegated to the bench at the weekend.
Watford captain John Eustace is set to return for the trip to face former manager Brendan Rodgers at Swansea.
Eustace missed the 1-0 win over Millwall at the weekend through a one-match ban but is available again for the trip to Wales.
Fellow midfielder Stephen McGinn began a lengthy lay-off on Saturday after he suffered a serious knee ligament injury which has ended his season.
On-loan Manchester United man Danny Drinkwater suffered a thigh injury in the same match at Doncaster 10 days ago so striker Troy Deeney played on the right of midfield against the Lions and could do so again.
Full-back Lloyd Doyley remains sidelined with a hamstring injury so youngster Adam Thompson will continue to take his place.