Brentford again proved their penalty prowess as they booked their place in the Johnstone's Paint Trophy Southern Section Second Round.
Richard Lee again proved to be the hero, saving one from Milton Keynes Dons substitute Darren Potter after a rip-roaring tie had finished 3-3
Gary Alexander, Jonathan Douglas, Jake Reeves and Mike Grella scored for The Bees and Stephen Gleeson smashed the decisive kick over the bar to send the visitors through.
It completed a hat-trick of sorts for Alexander as he scored two second half goals as The Bees came from behind to lead ten-man MK.
Former Bee Charlie MacDonald gave The Dons the lead in the first half and Luke Chadwick restored it after Adam Thompson had equalised for Brentford on his début.
The Dons had Shaun Williams sent off in first half stoppage time and Brentford looked like they had done enough as Alexander struck twice after the break.
But Jonathan Douglas scored an own goal with five minutes remaining as MK forced spot kicks.
Douglas redeemed himself by scoring for The Bees from 12 yards as they did enough in the shoot-out to back up last season's four wins in five penalty competitions with a win to start their JPT run.
The game started in a reasonably even fashion - the home side were a little more incisive but Brentford had their fair share of possession.
MK had the better of the chances and Lee had to make a brilliant early save to keep out a Dean Bowditch volley while Jay O'Shea had a shot saved and another blocked.
Marcus Bean volleyed wide for Brentford who were threatening, particularly when Harry Forrester got on the ball, without opening the home side up.
Adam Chicksen nearly scored the opener when he burst in to the box and fired in a shot that Marcel Eger and Thompson combined to block over the bar but the hosts didn't have to wait long.
O'Shea fizzed the resulting corner in to the near post and MacDonald rose unchallenged to head in.
Kevin O'Connor made a vital block to prevent George Baldock extending the lead with a fierce volley and that proved crucial as Brentford equalised soon after.
Myles Weston had already robbed the home defence and brought a low save out of David Martin and when Brentford pressed The Dons' again soon after a won a corner, they levelled.
Forrester lifted the ball to the back post when Thompson, again unchallenged, bounced a header past Martin and his defenders on the line to level.
Unfortunately for The Bees, the equilibrium didn't last long.
Luke Chadwick got a lucky ricochet in midfield and burst past Karleigh Osborne, he fired a low left foot shot past Lee to restore MK's lead.
That could have deflated Brentford but they responded well.
Weston was just unable to reach a delicious Forrester cross and a Douglas shot deflected inches wide, although assistant referee Robert Ellis adjudged it had hit Alexander, who was in an offside position, so it would not have counted.
The game swung Brentford's way moments before half time.
It came from an MK attack when Chadwick miss-controlled on the edge of Brentford's penalty area, Bean cleared long and Williams pulled down Weston as he raced clear.
Referee Lee Collins had no option but to send him off with the Brentford striker bearing down on goal.
The Bees nearly equalised before the break - Martin superbly tipped a Eger volley over the bar, then flicked a Forrester cross off his head before Alexander had a volley saved.
O'Connor had to make a vital block just after the re-start to stop Chicksen finishing off a break but the game was largely played in MK's half.
O'Connor had a shot blocked and Alexander headed wide but ten minutes in to the second half, the goal came.
Forrester picked out a delightful pass, Alexander skipped in behind the defence and slotted it low past Martin.
O'Connor nearly latched on to a similar pass soon after while Eger made a vital tackle to stop MacDonald scoring from another MK break.
Chadwick curled a couple of efforts wide as MK looked to try and win it but chances were coming at both ends.
Weston should have given Brentford the lead when Martin miss-kicked and presented him with the ball ten yards out but the stopper recovered to save low down.
Osborne had a volley blocked soon after and when Jake Reeves fired the ball back towards goal, it broke to Eger and but for a superb tackle from Tom Flanagan, the German would surely have scored.
Potter curled a free kick over and Reeves fired over from 30 yards as both teams sought the winner to avoid penalties.
Brentford thought they had got it when Alexander nodded home a superb Craig Woodman free kick but MK hit back.
They worked the ball down the right and George Baldock put in a fantastic ball and Douglas could do nothing but poke it in to his own net.
Brentford continued to push forward looking for another goal and Reeves shot wide from distance as they pressed while Bowditch had a shot blocked at the other end.
Bean thought he had won it in stoppage time when he met a Sam Wood cross with a powerful downward header but Martin somehow saved and he kept and Eger header to ensure it went to spot kicks.
But Martin couldn't repeat the dose when faced with Brentford's spot kick experts, Lee won out and The Bees progressed.
Milton Keynes Dons: Martin; Smith, Flanagan, Williams, Chicksen; Chadwick, Baldock; Powell (sub Lewington h/t), Bowditch, O'Shea (sub Potter 62 mins); MacDonald (sub Gleeson 62 mins)
Subs (not used): Bragg, MacKenzie
Bookings: Smith (81 mins)
Sent Off: Williams (45 mins)
Brentford: Lee; Thompson, Eger, Osborne, Woodman; Bean, Douglas, O'Connor (sub Reeves 62 mins), Forrester (sub Wood 78 mins); Alexander, Weston (sub Grella 66 mins)
Subs (not used): Moore, Spillane
Attendance: 4,175 (351 Bees fans)
By Chris Wickham