Macclesfield were unable to recreate the magic of last month's FA Cup win over Crystal Palace, with a Sam Heathcote own goal sending Brentford through to the fifth round after a spirited contest at Moss Rose.
Premier League side Brentford sat 116 places above the National League North team at the start of the evening - one less than the Palace side who were famously humbled here in January - but the gulf between the teams was turned on its head as John Rooney's part-timers dominated the first half.
A Bees side showing seven changes could not match the will or the skill of a Macclesfield team with a taste for giant-killing and the promise of a fifth-round trip to West Ham awaiting.
But they were not quite able to steal a lead and were unable to keep their fierce tempo as the game progressed.
Keith Andrews' team were far from top-flight standard but they set up camp in the final third and probed until something fell their way. It came in the 70th minute, Aaron Hickey finding space on the left and firing in a cross which the unlucky Heathcote glanced agonisingly past his own keeper.
