GER Brennan saw red, Stephen Cluxton missed a penalty but Bernard Brogan's class helped Dublin see off the challenge of Mayo tonight at Croke Park.
Brogan, the 2010 footballer of the year, scored 1-10 in a virtuoso display as Jim Gavin's men preserved their 100pc start to the National League with Mayo left to rue some poor shooting in a 2-14 to 0-16 win.
Brogan set the ball rolling the opening two scores of the game as Dublin led by three but six unanswered points from Mayo with Jason Doherty in particularly good form.
Brogan, Cian O'Sullivan and Paddy Andrews added points before Brogan swooped for the game's opening goal.
Mayo responded well and Michael Conlon's point meant they trailed by 1-8 to 0-8 at the break.
James Horan's men dominated the early stages of the second period with Kevin McLoughlin impressing as they regained the lead and their caused was helped after Ger Brennan was dismissed for elbowing Donal Vaughan.
Dublin were then gifted a chance to retake the lead within minutes of being reduced to 14 but Stephen Cluxton saw his penalty expertly saved by Kenneth O'Malley.
They didn't have to wait long for another goal as the next score was a goal from Kevin McManamon to put the Dubs 2-9 to 0-14 in front.
Brogan and Paddy Andrews then pointed Dublin to victory as Lee Keegan blew any chance of a Mayo comeback by blazing a ball over when one-on-one with Cluxton and Dublin ran out 2-14 to 0-16 winners.