Cardiff, from the National Division of the FA Women's Premier League, arrived at Harlow Town FC as favourites against Spurs, from the Southern Division.
But they were made to fight all the way before late goals secured a somewhat flattering 4-0 final scoreline in the third round encounter.
The ladies now have to pick themselves up for an important FAWPL fixture against Lewes at Harlow this Sunday as they sit at the wrong end of the Southern Division table.
Coach Juan Amoros is confident though. "As we all know, football is not always fair," he said. "The girls put a fantastic performance and ended up losing 4-0.
"That's hard to explain but if we put in the same display against Lewes I'm sure the score will be completely different. This is a key match for our season and we are already working on it."
Back to the FA Cup and chances were few and far between in a tactical first half against Cardiff, but the visitors showed their clinical edge to open the scoring through Kayleigh Green in the 16th minute.
The first 30 minutes of the second half belonged to Spurs. Bianca Baptiste fired just wide, Cardiff goalkeeper Rhian Nokes saved from Davina Smith and Sam Pittuck saw a goalbound header cleared off the line.
Bianca also had a goal disallowed from Davina's cross as the home team poured on the pressure.
Unfortunately, Cardiff scored the key second goal with their first notable attack of the half as Paige Stewart struck against the run of play with 18 minutes remaining.
Nadia Lawrence made it 3-0 in the 80th minute with Zoe Atkins completing the scoring late on.
Spurs Ladies: Ayre, O'Callaghan, Pittuck, Downie, Lane, Cheeseman, Schillaci, Cooper, Smith, Marcoci, Baptiste. Subs: Heath, M Kmita, Burr.