They opened the scoring after just 90 seconds when Jacob Fallaize met a Fin du Port free-kick in emphatic style.
Debutant Seb Sheppard won plaudits for his performance in goal as the Green Lions repelled a series of chances for their opponents.
Southall made the pressure tell in the second half to bring things level on 56 minutes when Brendan Matthew hit home a ball cut back from the left hand side.
GFC then conceded a penalty when the referee spotted a handball, but the resultant effort struck the bottom of the post.
The backline continued to hold strong and the game ended 1-1, leaving the Green Lions still in 21st place in the Isthmian South Central, but with their games in hand there is a chance they can pull themselves out of the relegation spot over the next two games.
They face Horndean at Footes Lane on Wednesday. Kick off is at 7.45pm.