United's clash with the Millers will take place on Tuesday 4th October, with a 7:45pm kick-off.
The venue is the Don Valley Stadium in Sheffield, where United's South Yorkshire counterparts have been playing their football since 2008.
Effectively, it is more of a home game for Danny Wilson's men that it is for Andy Scott's, with the DVS just 3 miles away from Bramall Lane.
The Blades have faced Rotherham at Don Valley before though, in a pre-season friendly last year - goals from Johnny Ertl and Daniel Bogdanovic secured a 2:0 win for United.
Like United, Rotherham have had a storming start to their league campaign, with both clubs lying second in Leagues One and Two respectively.
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