Goals at the end of each half saw Shamrock Rovers continue their climb from the lower reaches of the Premier Division yesterday.
The win was achieved amid controversy, with Derry players claiming there had been a second ball on the pitch at the time. However, following 15 minutes of deliberation after the game, the 2-0 result was allowed to stand.
Chasing three points to move into second spot, there was plenty of urgency about Derry in the early stages with the two wings backs, Eddie McCallion and Sean Hargan, taking the game to the home side. It was McCallion who was presented with the first chance of the game after three minutes, but having cut inside, his shot went straight into the hands of Robbie Horgan.
The goalkeeper was again called upon when forced to tip a Hargan cross over the bar. Rovers, looking uncomfortable in defence, continued to ride their luck, with Eamon Doherty having an effort blocked. The best they could offer in response inside a rather one sided opening quarter came when Tony Grant cut in from the left but, having chosen to go it alone, he directed a rather tame shot straight at goalkeeper John Connolly.
But as the half wore on, Rovers became more prominent, with Marc Kenny testing the Derry defence with some incisive play on the right. Four minutes before the break, his accurate cross found Derek Tracey, but the midfielder directed a header straight over the crossbar.
On 43 minutes, a calamity of errors inside the Derry box led to Rovers' opening goal. John Connolly spilled an effort from Billy Woods, throwing the Derry defence into a state of confusion, and after a protracted game of pinball inside the penalty area, Colwell found the back of the net at the second time of asking.
There was little goalmouth action after the break, and, despite the subsequent Derry protests, Rovers ensured victory in the dying seconds when Tony Grant fired home from an acute angle.
SHAMROCK ROVERS: Horgan; Smith , Palmer, Cronin, Woods; Kenny, Colwell, Tracey, Byrne; Francis, Grant. Subs: Robinson for Colwell (60 mins), Deans for Kenny (90 mins).
DERRY CITY: Connolly; McCallion, Kelly, Hutton, Harkin, Hargan; McLaughlin, Doherty, Hegarty; Parkhouse, Beckett. Subs: McCaul for McCallion (80 mins), Devlin for McCaul (85 mins).
Referee: P Kelly (Dublin)