Nicky Maynard came off the bench to earn MK Dons a replay against Northampton with a late equaliser in a pulsating 2-2 draw.
Both sides had early chances, Rob Hall tested Cobblers 'keeper Adam Smith, while Nicky Adams headed straight at Cody Cropper.
The Championship side took a 13th-minute lead when Lee Hodson's cross was turned into his own net by Ryan Cresswell, with Simon Church making sure the ball was over the line.
Hall fired just past the post moments later while Sam Hoskins saw his goalbound effort deflected wide, before Marc Richards glanced a header wide.
The Cobblers found the equaliser just four minutes after the restart. John-Joe O'Toole won possession and fed Hoskins, who set up Ricky Holmes, and he curled the ball around Cropper and into the top corner from 15 yards.
Moments later Richards curled one over Cropper's bar as the League Two side looked to get their noses in front.
And they did just that in the 58th minute when a neat move ended with Richards and Hoskins combining to release Holmes, who beat Cropper with an angled drive from 10 yards.
Dons boss Karl Robinson threw on Maynard in a bid to get back into the tie, but Northampton twice went close when Adams fired over, before O'Toole was denied by Cropper.
Maynard saw his free-kick saved by Smith before he broke through to chip the Northampton 'keeper, but Rod McDonald cleared off the line.
However, Maynard earned a replay in the 82nd minute when his fierce shot was deflected past Smith.