Buveur D'Air made a seamless transition back to the smaller obstacles with an effortless victory in the Betfred-sponsored Contenders Hurdle at Sandown.Despite having won his first two races over fences, trainerNicky Henderson only decided a few days ago to make the switch to see if he is a feasible contender for the Stan James Champion Hurdle. It proved the right call as the 1-4 favourite cruised past the pacesetting Rayvin Black with consummate ease to book his place in next month's Cheltenham Festival showpiece with a facile length-and-a-half success.Irving was third, with Hurry Henry a tailed-off last of the four runners.