Cesar Azpilicueta scored in the 87th minute to put the Blues ahead, marking the 19th time a defender has scored for the Blues since the start of last season.
That number is higher than any other club in the top-flight, with Azpilicueta at the forefront of creating goals — he has netted once this season and also laid on four assists.
This season, Azpilicueta and David Luiz have both scored once, while Marcos Alonso has two goals to his name — both scored in the club's early-season 2-1 win over Tottenham.
19 - Since the start of last season, Chelsea have scored more Premier League goals via defenders than any other team. Bonus.— OptaJoe (@OptaJoe) October 21, 2017
5 - Cesar Azpilicueta has been directly involved in more PL goals than any other defender this season (5 - 1 goal, 4 assists). Rampage.— OptaJoe (@OptaJoe) October 21, 2017
Chelsea's win over Watford moves them fourth in the Premier League table, ahead of the Hornets, and six points behind leaders Manchester City.