Derry City 0 Cork City 1: For the second week running Derry City suffered another defeat - this time to Cork City Foras Co-op.
However, unlike last weekend, their lead at the top wasn't cut as second placed Monaghan United were also defeated at Shelbourne.
The biggest movers in the First Division were Limerick, who have now also closed the gap to seven points.
Worryingly for boss Stephen Kenny, the Brandywell men look as though they have started to get nervous, as the season heats up and with two tough trips to Limerick and Waterford United in the next few weeks, the Derry gaffer will be hoping for better days.
City gave former Northern Ireland Under-21 international Danny Lafferty his first start since his return from Celtic.
The Brandywell men went close to breaking the deadlock on 12 minutes, but Patrick McEleney's 20 yard drive was pushed around his post by Mark McNulty.
On 28 minutes, Kenny's side upped the tempo to create a clear cut chance.
A fantastic flowing move by Derry ended with Eddie McCallion's cut-back finding Kevin Deery and his low centre fell perfectly for Mark Farrren, but from only 10 yards he screwed his shot wide.
The visitors took an undeserved lead with their first effort at goal on 53 minutes when George O'Callaghan's corner found Greg O'Halloran and the centre-back's header clipped off the post and nestled in the back of Gerard Doherty's net.
That goal meant Derry brought on Michael McCrudden for Darren McCauley, as Kenny attempted to spark some life into his team.
On 77 minutes Kenny introduced ex-Institute frontman Stephen Parkhouse for McEleney.
The Candystripes were unlucky on 85 minutes when James McClean's shot would have found Farren, but for a timely clearance by O'Halloran.
DERRY CITY: Doherty, McCallion, Scoltock, McChrystal, Lafferty, McBride, McCauley, Deery, P McEleney, McClean, Farren. Subs: McCrudden (for McCauley 58), Parkhouse (for P McEleney 77), S McEleney (for McBride 79).
CORK CITY: McNulty, Turner, O'Halloran, O'Neill, Duggan, Cummings, O'Callaghan, Lordan, Woods, Kavanagh, Barrett. Subs: Morrisey (for O'Callaghan 69), Cambridge (for Barrett 82).
Referee: Paul Tuite (Dublin).