The Millers are winless in seven, but that has to change in South Wales against a Cardiff side looking to finish a mixed campaign in seventh place.
With the top two spots sealed and the top six already known, the only issue left to be decided on the final day of the Championship season is who will be relegated.
Wycombe Wanderers are effectively down, barring a basketball-style score against Middlesbrough, leaving three teams battling to avoid the two other relegation spots.
Sheffield Wednesday and Derby County, positioned either side of Rotherham United, face off at Pride Park in a huge clash elsewhere on Saturday lunchtime.
Not only do Rotherham need to beat Cardiff, they also need Wednesday to take at least a point off Derby in that showdown in the East Midlands.
United could have been safe by this point, but they failed to take advantage of a number of games in hand on the sides around them and their fate is no longer in their own hands.
Paul Warne's men drew 0-0 with Luton Town in the most recent of those games in hand in midweek, making it back-to-to draws after being held at home to Blackburn Rovers.
That followed a run of five successive defeats, four of those without scoring. Now, from somewhere, the Millers have to pick up a first victory since April 13.
Cardiff may not have a great deal to play for on the face of it, which has been the case for a few weeks now, but they will want to end the season on a high.
The Bluebirds were expected to match or better last term's playoff semi-final spot, but they were made to pay for a poor start to the campaign under Neil Harris.
Harris has since been replaced by Mick McCarthy and, despite a big upturn in results around February time, City have fallen well short of finishing in the top six.
On the back of beating Wycombe and Birmingham City in their last two games, however, the Welsh side can still overtake Reading and finish seventh if results go their way.
The 4-0 win at Birmingham City last weekend was particularly impressive, inspired by a Harry Wilson hat-trick, and McCarthy will hope for a similar display on Saturday.
Cardiff have won their last three league matches against Rotherham United, including a 2-1 win in February's reverse fixture, scoring nine times and conceding just twice.
It would be incredibly harsh to leave Wilson out on Saturday, but McCarthy will be looking ahead to next season and may opt to name Cardiff's loan players among the substitutes.
As for Rotherham, Warne also freshened up his side last time out, albeit with the intention of sparking an improvement from his players, rather than with a view to the long term.
Matt Olosunde was among those recalled to the starting lineup against Luton and the visitors may well stick with a similar XI for this trip to the Welsh capital.
Cardiff City possible starting lineup:
Phillips; Morrison, Flint, Nelson; Ng, Pack, Ralls, Brown; Colwill, Murphy; Moore
Rotherham United possible starting lineup:
Blackman; Ihiekwe, Wood, Harding; Olosunde, Wing, Barlaser, Giles; Crooks, Wiles; Smith
We say: Cardiff City 2-0 Rotherham United
Rotherham are fighting for their lives and need to win at the Cardiff City Stadium to have any hope of staying up at the expense of Derby.
With the pressure off, Cardiff have won two games in a row - scoring six times in the process - and we can see the Bluebirds relegating their opponents here.
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