Derry City failed to close the gap at the top of the Premier Division as they were held to a 1-1 draw with league leaders Shamrock Rovers at the Brandywell.
Cameron McJannet's thumping header just after the hour gave Derry the lead.
Adam O'Reilly spurned a golden chance to double Derry's advantage moments later and it proved costly.
Graham Burke equalised late on from the spot with Shane McEleney sent off for his foul on the Rovers attacker.
City remain four points behind the champions with six games left to play.
Having gone six games unbeaten in the league since a 1-0 defeat away at Rovers at the end of June, Derry went into tonight's game knowing that a victory would set up a grandstand finish to the season.
The biggest Brandywell crowd of the campaign saw them start the stronger, calling visiting keeper Alan Mannus into action on a couple of occasions, albeit straightforward.
The away side grew into the contest and had the best opportunity of the first period just shy of the half-hour mark.
A corner caused chaos in the City area with Rory Gaffney taking two stabs at the loose ball and would have netted but for McJannet's goal-line clearance.
At the other end a finely worked corner routine saw Will Patching pick out Diallo at the back post, but his shot was blocked by teammate Danny Mullen.
Aiming to stop the Dubliners' quest for a fourth title in succession Ruaidhri Higgins' side took the lead in the 61st minute when McJannet climbed highest to send a thumping header flying past Mannus.
City had won three of the last five meetings on Foyleside prior to tonight's clash and Adam O'Reilly should have put the game to bed moments later.
With only the keeper to beat and despite Paul McMullan waiting in the centre, O'Reilly backed himself but fired disappointingly wide.
The door was left open and against the run of play, the Hoops made Derry pay.
Burke broke free and was brought down by McEleney with the referee pointing to the spot and sending the Candystripes defender to the sideline.
Burke dusted himself down and converted from 12-yards to bring the sides level.
With six games each left to play, Rovers maintain their four-point cushion, and City's hopes of league success are fading.