Frankel maintained his 100 per cent record as a sire over jumps as Commentariolus made a winning debut in a maiden hurdle at Fairyhouse.
A maiden on the Flat in France, he was heavily supported late on into odds of 9-2, despite the fact his stablemate Park Paddocks was morning favourite before drifting in the betting.
Having looked green at certain stages, he showed a smart turn of foot when asked a question by Keith Donoghue and won snugly in the end.
Free Ranger was four and three-quarter lengths away in second, with Park Paddocks third.
Trainer Gordon Elliott said of Commentariolus: "He won anyway so it's grand. He probably wants softer ground.
"We'll have a bit of fun with him and hopefully he'll win something else again.
"We'll try and find another little race for him somewhere. That probably wasn't the strongest race."
The only other runner Frankel has had over hurdles is Dan Skelton's Solo Saxophone, who is unbeaten in two races and is being aimed at the Fred Winter at the Cheltenham Festival.