The Royals drew 0-0 with Walsall at the Bescot Stadium on Saturday so must replay in right days time to see who takes the place in Round Four.
Getting Walsall was seen by many as a bad draw because the Saddlers lack the glamour of a top Premiership side. Anyone who was hoping for some glamour in the Fourth will be disappointed as the Dons are possibly the least glamorous proposition in the league!
Reading fans will console themselves with the fact that if they see off Walsall then the Dons are likely to put up limited resistance. A win would put the Royals into Round Five, just one victory short of a Quarter-Final place.
Meanwhile, local side Farnborough Town have been drawn at home to Arsenal in the tie of the round. The conference outfit have been richly rewarded for beating Darlington 3-2 on Saturday.
The tie may yet be moved to Highbory or even the Madejski Stadium as Cherrywood Road, which has a capacity of 4,163 may not be considered up to hosting such a high-profile match.
The Full Fourth Round Draw
Norwich or Brighton v Plymouth or Dagenhan & Redbridge
Southampton v Cambridge United or Millwall
Walsall or Reading v Wimbledon
Blackburn v Bolton or Sunderland
Rochdale v Cardiff or Coventry
Fulham v Charlton
Sheffield Utd v Ipswich Town
Shrewsbury v Chelsea
Stoke v Bournemouth or Crewe
Brentford v Grimsby or Burnley
Farnborough v Arsenal
Manchester United v West Ham United
Gillingham or Sheffield Wednesday v Leeds United
Wolves v Leicester City
Watford v West Brom
Crystal Palace v Liverpool