Rohan Ricketts' opportunistic winner leaves champions Shamrock Rovers within 90 minutes of retaining their title after they all but ended Derry's challenge at Tallaght Stadium.
Now four points clear at the top of the table, Michael O’Neill’s Hoops will be going for the league when they travel to UCD on Monday week.
There was little between two very committed sides in a frenetic first half with Derry, despite losing the services of winger Gareth McGlynn, shading affairs having created marginally the better openings in a very tight first 20 minutes.
Jim Paterson did well to make a terrific tackle on the in-rushing McGlynn before Derry carved the best chance of the first half on 37 minutes and were unfortunate not to score.
Eamon Zayed met a super cross in from the left by Daniel Lafferty to see his header come off a post with Dan Murray scrambling the lose ball clear.
Rovers had claims for a penalty waved away following an inconclusive looking handball by Barry Molloy from Ronan Finn’s cross three minutes later.
All Derry’s positive endeavour in the latter part of the first half was then undone when they gifted Rovers what would prove the winning goal four minutes into the second half.
Brush’s long clearance was allowed to bounce through by central defender Stuart Greacen. Unbeknown to the Scot, though, was the run of Ricketts who could scarcely believe his good fortune as he lobbed the advancing Ger Doherty to score from the edge of the area.
Rattled, Derry might have been 2-0 down four minutes later. Gary Twigg headed a Ricketts free-kick back across goal. Positioned dead in front of goal, Sives looked certain to score. His first time shot though was straight into the arm of Doherty straight in front of him.
Rovers were bossing Derry around now and Ryan McBride bravely got his body in the way to block a stinging shot from Twigg.
Their own title hopes slipping away, Derry, who’d lost control of midfield, struggled to respond as Rovers remained dangerous on the counterattack.
One such riposte almost brought Rovers a second on 80 minutes. Twigg threaded Finn in on goal with Doherty keeping Derry’s hopes alive with a vital save with his feet.
Shamrock Rovers: Brush; Sullivan, Sives, Murray, Paterson; Finn, Rice, Turner, Ricketts (McCabe, 74 mins.); Sheppard (Dennehy, 84 mins.), Twigg.
Derry City: Doherty; S. McEleney, Greacen, McBride (Higgins, 76 mins.), Lafferty; McGlynn (Farren, 36 mins., Harkin, 76 mins.), Molloy, Deery, McLaughlin; Zayed, P McEleney.
Referee: Alan Kelly (Cork)
