Rotherham academy product Jerry Yates came back to haunt his former club as he grabbed the winner in Swansea's 2-1 victory.
Defender Daniel Ayala was sent off for the Millers after 17 minutes and that changed the complexion of the game, with Swansea eventually taking full advantage to secure all three points.
The game saw two interim bosses in charge, with Rotherham believed to be closing in on the appointment of Leam Richardson.
- Championship fixtures | table | highlights
- Stream the Championship and more with NOW
- Get Sky Sports | Download the Sky Sports App
Wayne Carlisle took charge of his fourth Rotherham game following the dismissal of Matt Taylor, while Alan Sheehan was in the dugout for the Swans after the sacking of Michael Duff.
Christ Tiehi was first to force a save in the match as he latched onto a long throw and connected with a strong half-volley which goalkeeper Carl Rushworth was able to gather.
Rotherham were dealt a blow in the 17th minute when Ayala was shown a second yellow card for blatantly fouling Charlie Patino.
Swansea looked to make the most of the extra man and Yannick Bolasie came close to putting them ahead as he met Jay Fulton's cross to the back post.
Keeper Viktor Johansson had to deny Jamal Lowe with a strong save after the striker had closed down Cohen Bramall's attempted clearance.
Swansea continued to threaten before the break and Harry Darling should have done better as he rose highest at a corner only to head straight at Johansson.
The Sweden international was called into action again as he had to palm away Fulton's vicious shot from distance.
Johansson then clawed out Lowe's header superbly, but he could do nothing to prevent the opener a minute into added time when a cross from Jamie Paterson was deflected in by Patino.
Rotherham's protests over a handball were ignored by referee Josh Smith.
The Welsh side looked to put the game to bed early in the second half and it was a stinging effort from Darling which first troubled Johansson.
Instead it was the Millers who levelled after 64 minutes, with Sam Nombe tucking home after Hakeem Odoffin had gone up for a flick on.
Darling again threatened at the other end as he headed on target from Matt Grimes' corner.
Swansea went back ahead in the 73rd minute with Yates able to lash home after Lee Peltier failed to get enough on Josh Key's centre.
Rushworth was called into action in stoppage time as he pushed Georgie Kelly's header over the crossbar.
The managers
Rotherham caretaker Wayne Carlisle:
"Some of the big decisions, that is where the game hinges and it turns, went against us. But I can't fault the lads' effort.
"Later in the game we started pushing them back and putting them under pressure.
"I thought we started really brightly. But if we go in at 0-0 at half-time we would have been able to restructure. Two big decisions have cost us."
Swansea's interim head coach Alan Sheehan:
"I'm so proud of the players, staff and the whole football club. The support I've had from everybody has made that possible.
"We have stood up to a physical team. I think if we had been more clinical it could have been easier. We needed that second goal.
"They score from a long throw. They're a big physical team and we had to football our way out of it.
"We got the win. It has been a very difficult week and an emotional week. The overall feeling is pride."