Donegal Celtic moved five points clear of the Premiership basement after this stalemate at the Coleraine Showgrounds.
The hosts squandered early chances before DC boss Pat McAllister was dismissed from the touchline after protesting to referee Ross Dunlop.
David Scullion headed against the DC woodwork while Coleraine skipper David Ogilby was shown a straight red card for handball on 77 minutes.
DC's Peter McCann was denied late on by Ryan McIlmoyle's goal-line clearance.
There were few chances in a lacklustre affair with McIlmoyle creating the best first-half openings.
The winger sent in three pinpoint crosses but twice Allen and then Scullion failed to find the target.
McAllister was sent-off after 33 minutes when he reacted angrily to Dunlop's decision to allow play to continue following an injury to Sean Cleary.
Cleary went closest for the visitors in the first half with his flicked header going wide.
McIlmoyle was again the provider as Scullion's glancing header hit a post five minutes into the second half.
Coleraine played out the last 13 minutes with 10 men after Ogilby was punished when he handled to deny Stephen O'Neill possession.
McIlmoyle completed an impressive display by stretching to keep out McCann's goal-bound shot in the dying seconds.