Michael Smith and Freddie Ladapo both got a branch with defender Michael Ihiekwe also netting.
Rotherham leapfrogged fellow promotion hopefuls Sunderland with a stunning 5-1 victory.
Michael Smith and Freddie Ladapo's doubles alongside Michael Ihiekwe's header sealed the Millers the points over Lee Johnson's 10 men following Aiden McGeady's second-half dismissal.
Rotherham took a 10th-minute lead, with Smith heading into the far corner after a clever pass from Ladapo.
Sunderland struck back in the 24th minute, with Ross Stewart wriggling his way into the box and then driving a low effort beyond Josh Vickers.
Rotherham were back ahead on 41 minutes with Ladapo on hand to finish off from close range from Smith's low cross.
The two-goal advantage came in the 53rd minute when Ihiekwe powered in from Shane Ferguson's corner.
Sunderland were dealt a further blow in the 56th minute when McGeady lost his cool and received a second yellow card for lunging in late on Wes Harding.
Smith added further punishment as he headed in at the back post on 73 minutes from Rarmani Edmonds-Green's cross.
It was five on 88 minutes with Joshua Kayode rounding Ron-Thorben Hoffmann and unselfishly supplying Ladapo a tap-in.