Having overcome League One Walsall 3-2 in the previous round, Chris Wilder's men are available at 13/5 (3.40) with dabblebet to record a more high profile victory against their Premier League opponents.
Each of the visitors' last three matches in this competition have resulted in draws, and there are odds of 5/2 (3.50) available on them taking this one into extra-time with another stalemate.
Having won both of their league games at Bramall Lane by a narrow 1-0 margin, the Blades are already fighting hard to survive in the Championship after six years in League One.
Given this focus on league performance, it was no surprise that Wilder chose to make 11 changes for the Walsall match in the previous round.
With a big derby match against Sheffield Wednesday coming up at the weekend, the manager is sure to field a similarly rejigged line-up for this tie.
While Craig Shakespeare is likely to make some changes himself, whatever side he puts out should feel confident of causing problems for a weakened opposition back line that conceded twice against third tier opposition last time out.
Having called up young centre-back Josh White in the absence of the injured Wes Morgan and Robert Huth, Shakespeare's own defence may also have an unfamiliar look to it.
With neither team at full strength at the back, odds of 4/5 (1.80) seem generous on an understrength Sheffield United seeing another high-scoring cup clash that produces over 2.5 goals.