The question was quite how the game went to the wire after the ladies dominated from start to finish only to somehow find themselves 1-0 down at half-time.
Kate O'Leary finally broke through to level on 67 minutes but Copsewood Coventry's sheer will and determination in the face of wave after wave of attack kept them alive and took the match into the additional 30 minutes.
With only five minutes remaining Wendy Martin, who had already struck the crossbar in extra time, fired into the top corner to send Spurs through to the third round.
Below: Celebration time after Wendy Martin's late winner
Copsewood Coventry goalkeeper Rachael Graham played a starring role as the visitors kept Spurs at bay in the first half.
She denied Wendy Martin and tipped over from Bianca Baptiste, Wendy had a goal disallowed for offside, Andra Marcoci and Bianca were just off target and Sophie McLean broke forward from the right, played a one-two with Bianca and arrowed just wide.
Copsewood Coventry then scored with a bolt from the blue, a dipping volley from Sarah Harvey that flew into the top corner from 25 yards.
The second half was again completely one-way traffic. Avilla Bergin was first to try her luck, Wendy failed to connect with Kate O'Leary's cross and then Alex Keown rattled the crossbar from 30 yards.
The equaliser came midway through the half as Avilla broke down the left byline and crossed to the near post when Kate controlled, spun and finished from close range.
The ladies were now camped in and around Copsewood Coventry's penalty area but a flurry of chances failed to produce a winner.
Graham tipped over from Bianca, Dayna Chong fired just wide from Avilla's corner, Wendy headed over from Jenna Schillaci's free-kick, Kate chipped over from close range, Avilla shot just wide and Andra's 20-yarder fizzed just over, but it wasn't to be.
Extra time followed the same pattern. Andra shot straight at Graham, Wendy's 25-yarder clipped the top of the crossbar and Avilla was denied at point-blank range.
Just as time was running out in the second half of extra time, Wendy picked up the ball in the right angle of the area, controlled and unleashed an unstoppable shot into the top corner.
It was tough on Copsewood Coventry but any other outcome would have been a travesty.
Spurs Ladies: Toni-Ann Wayne; Sophie McLean, Alex Keown, Jenna Schillaci, Avilla Bergin; Shannon Maloney, Wendy Martin, Maya Vio (Dayna Chong, 76); Bianca Baptiste, Kate O'Leary, Andra Marcoci (Robyn Downie, 105). Unused sub: Tasha Smits.
More on Spurs Ladies at their dedicated microsite...