Wrexham's FA Cup win over Arsenal in 1992 was one of the biggest shocks in the competition's 153-year history, but can another Welsh team cause an equally monumental upset this weekend?
League Two side Newport County welcome Manchester United to Rodney Parade on Sunday, hoping to dump out the 12-time winners and end their last realistic hope of winning any silverware this season.
BBC Sport's football expert Chris Sutton has made his prediction for that game and the rest of the fourth-round ties.
For all 16 of the weekend's games he is up against Justin and Arni from indie band The Vaccines.