Rodgers spent four years as youth and reserve coach at Stamford Bridge before leaving to take the managerial reins at Vicarage Road in November.
The 38-year-old will not be the only familiar face for the visitors with Frank Lampard Sr, father of Chelsea's England midfielder, currently employed as Rodgers' football consultant.
Captain Jay DeMerit, who netted his first FA Cup goal in yesterday's 4-3 fourth-round win over Crystal Palace, believes the occasion will be one for the Hornets to relish.
He told Sky Sports: "It's a tough game of course but this is what we play for. Ever since I've been here we've never been short of cup runs and it's always good to get in these situations.''
