Rotherham stepped up their promotion push as Adam Le Fondre struck with his 24th goal of the season to earn a 1-0 win at the Pirelli Stadium.
Burton had the best of the limited scoring opportunities in hard-fought first half.
They were unable to capitalise on an indirect free-kick inside the visitors' area in the 32nd minute and gave the visitors an even bigger scare six minutes before the break.
Steve Kabba's shot came back off the legs of Rotherham keeper Any Warrington and young defender Tom Parkes headed the rebound wide from eight yards.
Le Fondre gave the Millers the lead in the 52nd minute by scrambling the ball over the line to punish poor defending by the home team after Warrington's long free-kick had bounced into their area.
The visitors quickly had chances to double their lead, but a Le Fondre header came back off a post and Burton keeper Artur Krysiak had to used his legs to deny Nick Fenton.
The Polish stopper produced more heroics to deny Le Fondre in the 74th minute as the Millers took control of the game.
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