Sligo Rovers boss Ian Baraclough hailed his side's "complete" performance as the reigning champions reclaimed top spot in the Airtricity League.
Lee Lynch, David Cawley and Ross Gaynor got the goals in a convincing display in front of 4,256 at the Showgrounds, as the Candystripes fell to a first league defeat since the Bit O'Red beat them in the Brandywell on the opening night of the season.
Baraclough said: "I think we stepped it up and took it to another level. These are the performances I have been asking for all season.
"The lads have been frustrated at times, and you could understand if there was a bit of edginess with them coming into the game, given recent results.
"But I thought that was our most complete performance this season."
Derry boss Declan Devine was left fuming that his side were not awarded a penalty with the game scoreless on 20 minutes.
Sean Houston released Barry McNamee and the Donegal native went down after slipping the ball past the dive of Rovers 'keeper Gary Rogers.
A penalty would also surely have meant a red card for Rogers, but instead referee Paul Tuite opted to book McNamee for diving.
To make it worse for the visiting fans, Tuite did award Rovers a penalty for a similar incident in the second half, while Shane McEleney was red-carded for taking down Cawley in the area.
Baraclough admitted: "We maybe rode our luck with one or two decisions that could have gone either way.
"The last few weeks they have gone against us, but you have to take the luck if you get it."
The sides could have had a couple of goals each in a cracking first half, but the only successful strike came from Lynch on 38 minutes.
Gavin Peers started the move, releasing Alan Keane down the right, who squared it inside the area for Pascal Millien. The winger's strike was blocked but the rebound bounced for Lynch to finish low into the corner.
The second half was a different affair, with Cawley sliding home the decisive second goal just eight minutes in, after a great cross from Millien.
Aaron Greene thought he had scored shortly before that, only to see his effort crash off the foot of the post.
But Gaynor wrapped it up from the spot after McEleney's red card, though substitute Liam Martin could have got a fourth late on, when he charged down Gerard Doherty's clearance and the ball came back off the woodwork.
Sligo Rovers – Rogers; Keane, McMillan (Henderson 88), Peers, Davoren, Millien, Lynch (Ventre 73), Ndo, Cawley, Gaynor (Martin 76), Greene.
Derry City – Doherty; Madden, McBride, S McEleney, McCaffrey, P McEleney (Duffy 62), Molloy, Houston, McNamee, Griffin (Rafter 62), Patterson.
Ref – P Tuite.