Colchester, bottom of the third tier League One, had been hoping to rekindle memories of one of the Cup's most famous upsets when, as a fourth tier club in 1971, they beat mighty Leeds United.
Yet after their two centre halves, Alex Wynter and Tom Eastman, collided early in the game and had to be substituted, the underdogs were outclassed by a strong Spurs side in the first half when a fine Chadli shot put them ahead in the 27th minute.
Despite also having their woodwork struck twice, the spirited home side seemed to be getting a foothold until Eric Dier's speculative 64th-minute shot took a cruel looping deflection into the net.
Chadli headed home Kieran Trippier's cross after 79 minutes before Colchester were finally rewarded for their efforts when Gavin Massey's shot hit the post and the ball rebounded off the shins of Spurs defender Ben Davies and into the goal.
Chadli rounded off his fine performance with a cross which enabled Tom Carroll to seal an emphatic triumph seven minutes from time.
The game provided a lively springboard for the weekend Cup programme which features Arsenal's continuing bid to win the trophy for the third successive year with a home tie against Burnley on Saturday.
There are three all-Premier League ties, Aston Villa hosting Manchester City, Liverpool entertaining West Ham United and Crystal Palace at home to Stoke City. – Reuters
Original source: Spurs ease past Colchester