Kyle Vassell struck twice as Rotherham crushed Oxford 3-1 at the Kassam Stadium to storm to the top of League One.
It was the Millers' fourth league win on the spin and came after a stunning opening 45 minutes.
The U's had not conceded at home in the league since last August but found themselves three goals down by half-time.
Vassell, who was on loan at Oxford five years ago, converted Chiedozie Ogbene's right-wing cross in the 16th minute with a crisp first-time finish.
The striker ran on to Dan Barlaser's ball through the middle to lob Simon Eastwood after 33 minutes and make it 2-0.
And in first-half stoppage time Vassell turned provider with a cross from the right that skipper Richard Wood tucked in from close range.
Shellshocked Oxford brought on new signings Nathan Holland and Marcus Browne for the second half and Browne pulled one back after 71 minutes, drilling in a low shot after Millers could not clear Mark Sykes' cross.