Here we take a look at some of the best and worst performances the Blades have produced in recent years in the third round of the world-famous competition.
1. Swansea City 2007
Premier League Blades slumped to a 3-0 reverse to League One Swansea City in a fiery home clash at Bramall Lane in January 2007. Picture Steve Parkin. Photo: STEVE PARKIN
2. Aston Villa, 2005
Sheffield United's Andy Liddell celebrates scoring the second goal in a 3-1 win over David O'Leary's Aston Villa at Bramall Lane in 2005. Photo: Gareth Copley/PA Photo: Gareth Copley
3. Barnet, 2019
Jubilant players from National League side Barnet celebrate their shock 1-0 win at Bramall Lane last season. Photo: Simon Bellis/Sportimage Photo: Simon Bellis
4. QPR, 2015
Blades boss Nigel Clough celebrates his side's stunning 3-0 win at Premier League outfit QPR in 2015. Photo: Martyn Harrison, Blades Sports Photography. Photo: MARTYN HARRISON