Portobello prop forward Cristian Maluk scored a try just before the final whistle to secure a bonus-point win for his team against Forrester on Saturday in RBS East One.
With the match approaching the final minute the hosts were 23-15 up, but desperately wanted to get their fourth try to make it a five-point victory.
And they did just that when Maluk went over and Rory Thomson converted to see the team into fourth in the table , leapfrogging North Berwick.
The match was a pretty tight affair at Cavalry Park, Portobello leading 11-9 at the break. As well as Maluk, fellow front-rower Chris Sinclair and wingers Keith Jeffrey and Rob Ritchie scored Porty’s tries with Thomson kicking ten points.
Preston Lodge are still top and have now won eight out of eight after a 29-13 home win over Trinity Accies. North Berwick, Ross High and Lismore all lost to Berwick, Duns and Hawick Linden respectively.
Leaders Dalkeith beat Moray House 83-7 in RBS East Two.
Edinburgh Northern beat St Boswells 57-7 to stay top of RBS East Three. Liberton beat Queensferry but Inverleith lost 17-6 at Walkerburn.