Derry City lost 2-0 at home to Sligo Rovers on Friday night in the Premier Division.
The defeat was Derry's first lose this season at home.
Goals by Rafael Cretaro and Jimmy Keohane gave Rovers the derby win.
Cretaro headed in on 26 minutes when he met a cross into the box from the left.
Keohane ran through the home defence and steered the ball by the keeper to net the second goal.
The defeat ended Derry's run of nine games unbeaten and it was the first time they had not scored under Kenny Shiels.
With leaders Dundalk beating Bohemians 2-0 and Cork City 1-0 winners over St Pats, Derry drop to third, five points off top and one point behind the Leesiders.