The Scholars were two minutes away from taking a hard earned point from a game in which they spent much of the ninety minutes on the back foot.
The best early chances fell to the home side with Bar struggling to cope with the pace, movement and passing of Tom Bird and Reece Hall on the left . But it was the Scholars who could have taken the lead on 13 minutes as a clever chip from Keegan Cole almost caught the home 'keeper unaware and off his line. Minutes later Brad Sach saw his shot fly just over after breaking free from the Merstham defence.
Just on the half hour a free kick from Hall was driven though the defensive wall producing a fine save from Berkely Laurencin. Merstham continued to apply the pressure but it was The Scholars who took the lead with 36 minutes gone. A pinpoint pass from George Nicholas found Dernell Wynter breaking into the box to slot home and put the visitors into the lead.
The second half again saw Potters Bar under pressure but generally coping well in defence with Steve Brown and Eoin Casey blocking all that came at them.
With the hour mark approaching The Moatsiders were level. A tremendous strike from Tom Kavanagh from 35 yards out beat the whole defence leaving the keeper Laurencin with little or no chance.
Half way through the half Bar looked to have a case for a penalty as Sandro burst into the box and appeared to have been impeded but the referee waved play on . A second shout came just minutes later as Sandro took advantage of a defensive mix up to play in Brad Sach who could claim to have been brought down but the Referee was equally adamant.
With three minutes remaining and with the point looking to have been secured Bar were hit by two further hammer blows . Tom Bird took advantage of a retreating defence to cut inside and drill the second for the home side again from near 35 yards out.
Into time added on and with the Scholars pushing to look for an equaliser Kershaney Samuels broke virtually the length of the field to put it beyond doubt with another great strike from distance.