The Dons booked a tie with Premier League champions Chelsea after overcoming Northampton Town 3-0 in their Emirates FA Cup third-round replay.
Second-half goals from Ben Reeves, substitute Josh Murphy and Simon Church saw off the Cobblers, who held the men from MK1 to a 2-2 in the original fixture.
Karl Robinson named a strong starting XI for the tie with skipper Dean Lewington, David Martin, Samir Carruthers, Rob Hall and Reeves all included. Kyle McFadzean was suspended while Darren Potter (knee) wasn’t risked.
The Dons were forced into a late change when Nicky Maynard picked up an injury in the warm up but the man that came in – Church – also got in early on but Adam Smith rushed off his line to deny the striker.
Martin comfortably saved a Sam Hoskins effort before, at the other end, Dean Bowditch was brilliantly denied at the back post after Hall had beaten his man and cut the ball back.
Bowditch almost got on the end of another Hall cross shortly afterwards as the men from MK1 began to look more dangerous in front of goal.
However, the Cobblers carried a threat of their own but the Dons were holding firm, with the next chance falling to Hall, who curled over after driving at the visitors’ defence.
Hall also saw a couple of balls into the dealt with while a low delivery from Reeves was stabbed away by Rod McDonald with Church lurking.
On a rare foray forward for the visitors, Martin easily gathered Ricky Holmes’ shot-cum-cross not long before the break.
The first action of the second half saw Brendan Moloney fire over from 25 yards, that came before the Cobblers had the ball in the net but it was ruled out for following a foul on Martin.
However, the Dons took the lead in the 54th minute when Reeves coolly home from the penalty spot after Bowditch had been brought down. 1-0.
The lead was soon doubled as substitute Murphy raced on to Samir Carruthers’ through-ball, steadied himself and slotted past Adam Smith from 12 yards. 2-0.
Northampton looked for a way back into the game and enjoyed some reasonable territorial advantage but the Dons held firm while also continuing to pose a threat going forward.
With just over 10 minutes remaining, Joe Walsh had to be alert to block a shot from Moloney as the Cobblers countered down the right-hand side.
Church wrapped up a comfortable victory, in the end, and ensured a tie against Chelsea with a smartly taken spot-kick after man of the match Hall had been brought down by keeper Smith.
MK Dons: Martin; Hodson, Kay, Upson (Walsh 38), Lewington (c); Carruthers, Forster-Caskey; Bowditch (Murphy 55), Reeves (Powell 75), Hall; Church.
Unused subs: Cropper, Spence, Murphy, Hitchcock.
Goals: Reeves (53), Murphy (62), Church (89).
Attendance: 15,133 (7,040 Northampton fans).
Man of the match: Rob Hall.
Referee: Tony Harrington.