But only Barnsley are definitely guaranteed to play in the next phase, after thrashing Burton 5-0 at Oakwell.
Sam Winnall grabbed a hat-trick for the Tykes, with other goals coming from Conor Hourihane and Devante Cole.
The Blades will need a replay at Bramall Lane after a 0-0 draw at Crewe, while York City will also get a second chance after being held 1-1 by Wimbledon.
Jake Hyde converted Michael Coulson’s cross, before Andy Frampton levelled the scores.
But for Doncaster Rovers, they had a wasted journey to Weston-super-Mare, as heavy rain saw the match called off just before kick-off.