Matty Smith put the Candystripes in front at the Brandywell on Friday night
Derry City lost further ground on the top two with a disappointing 1-1 draw at home to Drogheda United.
Three weeks removed from the 2-2 north-west derby tie with Finn Harps, Matty Smith steered the Candystripes ahead just after half an hour.
A Dean Williams penalty brought Drogheda level on 78 minutes and neither side could fashion a winner.
Derry remain third but winless in seven games and three points off Dundalk, who defeated leaders Shamrock Rovers 1-0.
"Very disappointing, the game should have been over after 10 minutes," said Derry boss Ruaidhri Higgins.
"When you don't take your opportunities you get punished and we got nervy in the second half because we weren't further in front and they clawed their way back.
"We need that winning feeling back. Again I know we didn't play brilliantly in the second half but we did create two, three really good chances and if you base it on chances and possession we should have won the game comfortably in a but we didn't."
Back in action
After a mid-season break City returned to the Brandywell, where they beat Drogs 2-0 back in March.
The visitors' goal was under siege in the early stages with Cameron Dummigan and Will Patching both going close.
Dean Williams ensured Drogheda left the Brandywell with a point after converting a penalty
Ruaidhri Higgins' men had failed to win any of their last four games on Foyleside but took the lead inside 33 minutes when the ball eventually came to Smith in the area and he lashed the ball into the roof of the net.
Drogheda had lost three of their last four matches away from home and almost fell further behind after the hour mark, only for Jamie McGonigle's effort to whistle past the post.
The sides drew 1-1 in the most recent meeting at Head in the Game Park and on 78 minutes they were level once again as Derry failed to put the game to bed.
Williams cut a lone figure for Drogheda throughout the evening but when Ryan Brennan was bundled over in the area the striker stepped up and sent Brian Maher the wrong way, slotting the ball into the bottom left-hand corner from the penalty spot.
McGonigle went close on a couple of occasions to snatch the victory for the hosts while James Akintunde's deflected shot went the wrong side of Colin McCabe's upright.
Derry have just taken 17 points from a possible 33 at home, winning four of their 11 fixtures as hosts and they now find themselves eight points off the summit with Dundalk the most likely challengers to Rovers.
