Frederick Engels was a major disappointment as Dabirsim maintained his unbeaten record with an emphatic win in the Darley Prix Morny under Frankie Dettori.

Once Dettori pressed the button the Group One race was over as Dabirsim took his 100% tally to four, showing a terrific turn of foot a furlong out.

Family One made a sterling job of trying to make all the running, but had no answer to the Christophe Ferland-trained colt, who swept by in the style of a potentially very smart performer.

Vladimir was third and Sofast fourth, with the David Brown-trained Frederick Engels only fifth having had every chance in the hands of Johnny Murtagh.

Murtagh had the Windsor Castle and July Stakes winner ideally placed in second early on, but he could not quicken when it mattered. The Mick Channon-trained Gatepost was last.