In a repeat of last season's semi-final, the ladies met higher-level Charlton from the National Division of the FA Premier Women's League.
Unfortunately, this time the result was reversed and Charlton will now face Arsenal Reserves in the final after a 4-0 win at Harlow Town FC.
The teams were evenly-matched until Charlton capitalised on defensive mix-ups in the second half, with two goals in as many minutes putting the issue beyond doubt.
Ebony Heath came to the rescue early on, clearing off the line from Gemma Bryan and Bianca Baptiste went close before Bryan opened the scoring, beating Jo Ayre one-on-one.
Influential midfielder Jessica Cheeseman then departed injured with Faye Picton making her debut off the bench.
Sam Pittuck then broke through one-on-one but was denied by Charlton goalkeeper Megen Lynch, with the Spurs player injured in the challenge.
Pittuck was denied again by Lynch at the start of the second half and Bryan took advantage of a lack of communication defensively to make it 2-0.
Kim Dixson made it 3-0 and after the departure through injury of Pittuck, Bryan completed her hat-trick.
Juan Amoros, Spurs Ladies Manager, reported: "We have some players out but it is not an excuse to concede three goals in the way we did. Now we will be focused just in the Premier League where every match is a final for us. We have six matches to finish and we have to play those matches as cup finals to stay in the Premier League."
The first of those matches is scheduled for March 10 and a trip to Colchester.
Spurs Ladies: Ayre, Smith, Downie, Heath, Burr, Cheeseman (Picton), Martin, Marcoci, M Kmita, Baptiste, Pittuck (R Kmita).