Marco Asensio scored a brace for the second consecutive game at Villa Park as Cardiff's resistance was finally broken on a successful debut for automated offside in England.
After Marcus Rashford had embarrassingly missed from four yards, the England forward recovered to set up Asensio for the all-important breakthrough midway through the second half, the new technology ruling instantly Rashford had been onside in the build-up.
Asensio, on loan from PSG, then settled the tie late on as Villa reached the FA Cup quarter-finals despite playing their fifth match in 13 days with a Champions League trip to Bruges coming up on Tuesday.