Both of these teams will feel that they have a decent chance of reaching round five of the FA Cup if they come through this replay at Brisbane Road.
For the winner, struggling Championship side Barnsley will stand between them and a place in the last 16 of the competition.
League One side Orient sprung a surprise during the first match between these two sides by claiming a 1-1 draw at the KC Stadium.
They will also be buoyed by the recent addition of experienced striker Charlie MacDonald, who has signed on for Orient from MK Dons until the end of the current campaign.
Travelling Hull could be without goalkeeper Eldin Jakupovic, who suffered a head injury during the weekend's encounter against Sheffield Wednesday.
Steve Bruce may also make a number of changes to his starting lineup, with Jay Simpson and Paul McShane in contention for a place in the team.
Recent form
Orient: WWLWLD
Hull: WWDWDL
Possible starting lineups:
Orient: Jones; Sawyer, Cuthbert, Baudry, Odubajo; Cox, Smith, Cook; James; MacDonald, Mooney
Hull: Jakupovic; Chester, McShane, Evans, Faye; Koren, Aluko, Elmohamady, Brady; Simpson, Proschwitz
Sports Mole says: 1-2
Liam Apicella
