Though rare, referees do get injured in the middle of a football match and get replaced by other match officials. Here are some cases.
1. On 5 November 2017, English referee Bobby Madley subbed himself off due to a thigh injury during the first half of the Premier League game between Stoke and Leicester.
2. On 26 January 2021, Italian referee Paolo Valeri was subbed off for the fourth official, after sustaining a thigh hamstring injury during the Coppa Italia match between Inter Milan and AC Milan.
3. On 25 July 2021, referee Ted Unkel was replaced by fourth official Matthew Thompson, after colliding with San Jose Earthquakes centre-back Nathan in an MLS match against Houston Dynamo.
4. On 27 February 2021, referee Lee Mason suffered a calf injury during West Brom’s 1-0 Premier League win over Brighton.
He managed to complete the game but was not available to start as the fourth official, as was planned for his next duty, a match between Sheffield United and Liverpool at Bramall Lane.