Sutton United, a team in the fifth tier of English league football, defeated top-tier Coventry City in one of the biggest upsets in FA Cup history.

Sutton United Football Club is a professional association football club from Sutton, South London, England. The team competes in the National League, the fifth level of the English football league system.

The English football league system, also known as the football pyramid, is a series of interconnected leagues for men's association football clubs in England, with five teams from Wales, one from Guernsey, one from Jersey and one from the Isle of Man also competing. The system has a hierarchical format with promotion and relegation between leagues at different levels, allowing even the smallest club the theoretical possibility of ultimately rising to the very top of the system, the Premier League. Below that are levels 2–4 organised by the English Football League, then the National League System from levels 5–10 administered by the FA, and thereafter Regional feeder leagues run by relevant county FAs on an ad hoc basis. It also often happens that the Premier Division of a Regional Feeder League has its constitution given to it by the FA. They have to accept it or appeal but cannot reject it at an annual general meeting.

The 1988–89 FA Cup third-round match between Sutton United and Coventry City was an association football game played at Gander Green Lane in Sutton, on 7 January 1989. Coventry City entered the FA Cup in the third round, as they participated in the Football League First Division, the top tier of English league football. Sutton United of the Conference, the fifth tier of English football, had started their cup run in the 4th Qualifying round, winning three ties to reach this stage of the competition. Coventry, the away team, went into the match as strong favourites, a reflection of the gulf in divisions that separated the two teams.

Coventry City Football Club is an English professional football club based in Coventry, West Midlands. The club plays in the EFL Championship, the second tier of English football. The club is nicknamed the Sky Blues after the sky blue colours that have featured prominently throughout their history, which they have worn continuously since 1962.