Adjutant caused a 50-1 upset when just edging out Why We Dream in the first division of the Dubai Duty Free Tennis Championships Maiden Stakes at Newbury.
Well beaten on his sole start for David O'Meara, the son of Champs Elysees showed a willing attitude for Jim Crowley when overcoming a 226-day absence to strike for the first time since joining Brian Meehan's stable.
The first two had the race to themselves in the final furlong and were only separated by a head as they pulled seven lengths clear of Coolongolook in third.
Mapped was fourth and the Queen's Humbolt Current, the 5-4 favourite, only fifth.
Meehan said: "We did some good work with him the other day and while everything was focused around the favourite, our horse battled to the line and he'll get further.
"David O'Meara trained him last year and I know he liked him. It was a pretty impressive performance and we might look at aiming him towards the Britannia (at Royal Ascot)."