Elsewhere, Manchester City hosts Leeds and Chelsea will travel to Middlesbrough if it can see off Brentford in a replay, while giant killers Luton faces Millwall at home.
|FA CUP FIFTH ROUND DRAW
|H'field or Leicester
If it can beat Brentford at the second attempt, Chelsea will face a trip to Middlesbrough in the last 16, while giant killer Luton, which knocked out Norwich, will play Millwall at Kenilworth Road.
MK Dons, which also put out a Premier League club in QPR, will face Barnsley at home while the winners of the replay between Huddersfield and Leicester will play Wigan.
That means the tie between Premier League leader United and struggling Reading is the only one to feature two top flight clubs after a weekend of surprise results.
On Friday, Aston Villa was dispatched by Millwall, before MK Dons and Luton sprung shocks away to QPR and Norwich respectively.
Their triumphs were followed on Sunday by Brentford's draw against Chelsea at Griffin Park and Oldham's 3-2 victory over Liverpool.
The fifth round fixtures will take place over the weekend of February 16 and 17.