Chelsea: Cech; Azpilicueta, Zouma, Cahill, Filipe Luis; Ramires, Mikel; Remy, Oscar, Schurrle; Drogba (c)
Subs: Courtois, Ivanovic, Ake, Matic, Willian, Salah, Diego Costa.
Watford: Bond (GK); Hoban, Cathcart, Angella; Paredes, Munari, Tozser, Forestieri, Pudil; Ighalo, Deeney (C).
Subs: Gilmartin (GK), Doyley, Murray, Vydra, Abdi, Doherty, Smith
Chelsea have won four of the five FA Cup ties they have played against Watford, including one after a replay.
The Blues have scored nine goals without conceding in two previous FA Cup ties against the Hornets.
The first meeting between Chelsea and Watford (March 1970) and the last (January 2010) came in the FA Cup.
Chelsea have lost only two of their last 33 FA Cup matches (W25 D6 L2), though one of the draws led to elimination on penalties by Everton.
Oscar has four goals and two assists in eight FA Cup starts for Chelsea.
In the last six seasons, Watford have been knocked out twice by Man City, twice by Chelsea, once by Spurs and once by Brighton.