They lasted until the final seconds when Eustace struck.
Earlier City went a goal up through Danny Haynes before Tom Cleverley levelled 2 mins before the break. City regained the advantage on the stroke of half time through Paul Hartley's super free kick.
Nyatanga's second yellow for a rash challenge on Lansbury saw the Watford player stretchered off and Nyatanga sent off.
Watford have a break from League action now and face a trip to Chelsea on the weekend in the FA Cup. No problem!!