Finishing bottom of the entire Football League the previous season, Wrexham escaped the clutches of relegation solely due to the expansion of the Football League and were expected to just drop straight back down.
In polar opposite circumstances, Arsenal celebrated winning the First Division in the season prior, losing just one game in the process making the London side overwhelming favourites in this one and creating a potential upset of the greatest calibre.
Thanks to an Alan Smith free-kick, the Gunners looked to be progressing into the next round with 10 minutes to go, however, the tie rapidly turned on its head as a free-kick from Mickey Thomas saw the host’s go level. Two minutes later, madness ensued as the Welsh side took the lead as George Graham’s side crashed out the cup in the third round in what he described as his darkest day in management.
Given the contrasting sides and how Arsenal were England's kings back then, it's arguably the biggest upset there's ever been.