Derby continued their perfect start to the season - their best for 106 years - sweeping Doncaster aside.
Veteran Kevin Kilbane opened the scoring in the sixth minute when he headed home a corner.
Steve Davies doubled the lead early in the second period with another header.
Ben Davies, who had created the first two goals, then got on the scoresheet when he struck from the edge of the area as the Rams made it four wins from four Championship fixtures.
Derby came into the game on the back of wins over Birmingham, Watford and Blackpool and there was no danger of it being anything other than another routine win as Nigel Clough's men dominated in front of more than 23,000 at Pride Park.
For Doncaster, it was a fourth straight defeat and they were made to pay for failing to make a period of first-half domination count.
Rovers are without a Championship win since their last visit to Derby at the start of March, 16 games ago.
The hosts started brightly and when Ben Davies whipped in a corner from the right, Kilbane climbed highest to powered home a header.
However, Rovers responded and Giles Barnes could have equalised but the former Derby man blazed over from a great position after good work from Chris Brown.
They were made to pay just 20 seconds into the second half as Derby doubled their lead when Ben Davies advanced down the left and earned his second assist by setting up Steve Davies to head home at the far post.
Ben Davies then capped a fine display by curling in a sweet effort from 20 yards just after the hour, and the rest of the game was comfortable for Clough's men.