Porter broke the deadlock when, against the run of play, and from Oldham's first meaningful attack, Richard Butcher crossed from the left flank for the young striker to rise unopposed and divert the ball into Stuart Nelson's bottom corner.
The home side levelled shortly afterwards with an early contender for goal of the season. Kevin O'Connor's free-kick was smashed into the wall; it rebounded into the path of Darren Pratley, who unleashed a spectacular right-foot volley into the bottom corner from all of 25 yards.
This goal proved to be a false dawn for the Bees, as five minutes later their back line once again failed to deal sufficiently with a high ball into their penalty area. Paul Warne eventually chipped the ball back where it was met by the head of Porter for his second goal of the afternoon.
Two minutes later, it got even better for the front man. Once again he rose unopposed to head home a Warne cross, drawing a chorus of boos from the Griffin Park faithful, and sparking a heated inquest amongst the Bees defence.
Brentford refused to give up and pulled themselves back into the game when Dudley Campbell made sure he was the first man to pounce on a ricochet in the box, firing hard and low past Chris Day in the Oldham goal.
After both defences had no doubt been given an ear bashing at half-time by bosses Allen and Moore respectively, the second half failed to live up to the excitement of the first.
For all of their second half endeavours, primarily from corner kicks, Brentford could not find a way back into the game. That is until the 89th minute and, with time running out; Lloyd Owusu headed home a corner from the left to earn the Bees a well deserved point.