St Patrick's Athletic moved four points clear at the top of the Premier Division after a hard fought win over Cobh on Saturday evening.
The only goal of the game came from debut boy Derek O'Brien, who scored after coming on as a half time substitute, putting away a shot from close range, high to the roof of James McCarthy's net.
St Pat's midfielder Keith Fahey was outstanding throughout, and almost added a second near the end, but was denied by Ramblers' goalkeeper McCarthy.
Ramblers came into the match with home League of Ireland debuts for midfielder Colin O'Brien signed on loan from Cork City, and Greg O'Halloran signed form Galway, both in until the end of the season to try and keep the club in the Premier Division.
St Patrick's had scored eight goals in their last two league outings, with Mark Quigley having netted seven in four league matches, including a hat-trick in their last away league win in Derry.
Ramblers, with manager Stephen Henderson serving the last of his four-match touchline ban, were without centre-back Shane Guthrie who was sent off in a Munster Cup final defeat against Cork City on Monday night.
The home side set out with a defensive formation of five men in midfield and just Graham Cummins up front, in the hope of containing the leaders.
After a scoreless first half of very few chances, Derek O'Brien found space at the far post in the 65th minute to plant a shot to the roof of the Ramblers net from six yards.
O'Brien had scored at the same end for his previous club Galway when he hit an equaliser against Cobh back in March, and this strike for Pat's pays back some of the €25,000 transfer fee shelled out by manager John McDonnell just a week ago.
The goalscorer kept taking on the home defence in the closing stages and had another shot saved by McCarthy, who denied the outstanding Keith Fahey with a fine stop after the midfielder danced past a couple of defenders.
Cobh introduced substitutes Daryl Kavanagh, the former Waterford player, and Ross Gaynor from Millwall, a former Irish U-21 international, and they switched to a 4-4-2 formation, but the Dublin defence stood firm for three vital points.