Verdana Blue has ended the long unbeaten run of dual champion hurdler Buveur D'Air in the Christmas Hurdle at Kempton with her owners eyeing a return to the flat and a start in the Melbourne Cup.

Both Verdana Blue and Buveur D'Air are trained by Nicky Henderson, and they had the race between them on Wednesday (Thursday AEDT) from the second-last jump.

The 1-4 favourite, Buveur D'Air looked as if he would just hold on but the mare got up to deny him by a short head.

Buveur D'Air had not been beaten over hurdles since the Supreme Novices' Hurdle in 2016.

"She is a very good mare and she always has been when you get her on decent ground, as she is no good on soft ground. Unless you can promise it will be good to firm it will be a waste of time (training for Champion Hurdle)," Henderson said.

Charlie Parker, who manages the interests of Verdana Blue's owners Climbourne Stud, said the Melbourne Cup was a long-range target for Verdana Blue who has raced on the flat twice in the past two years.

"The plan is to go to the Melbourne Cup," he told Racing UK. We might be mad but if she can win on the flat maybe we can go."

Verdana Blue is likely to run in the staying race at the All Weather championships on Good Friday.

She has already passed the first ballot clause for the Melbourne Cup with her second in the Listed Wild Flower Stakes (2400m) on Kempton's on December 5.