Gleneagles ably justified 4-7 favouritism in the three-runner Group Three Japanese Racing Authority Tyros Stakes at Leopardstown on Thursday evening.
The Galileo colt was beaten by the reopposing Convergence on his debut at Leopardstown in June but he reversed that form in the hands of Joseph O'Brien.
Gleneagles, who won a strong Curragh maiden on his second visit to the racecourse towards the end of last month, was last of the trio for a long way but made his move one and a half furlongs from home.
The Ballydoyle inmate had to work fairly hard late on, but he was always doing enough to keep Tombelaine at bay.
Convergence also shaped creditably as he was not beaten far at all in third.
The winning trainer said afterwards: "I'm delighted with that. Sometimes these three-runner races can be a bit messy, so he'll have probably learned plenty from it.
"They went slow early on and he picked up well, Joseph did the right thing in relaxing him and riding him to educate him.
"I'd imagine he'll improve a good bit from that, as he's still a bit babyish."
O'Brien indicated that the Goffs Vincent O'Brien National Stakes at the Curragh on 14 September could come under consideration for him.
Jack Naylor caused a 14-1 stir by winning the Group Three Jockey Club Of Turkey Silver Flash Stakes.
The Jessica Harrington-trained filly was delivered fast and late by jockey Fran Berry to get up in the final 100 yards and deny the onrushing Agnes Stewart.
Game frontrunner Qualify finished third, but Marsali, the 11-4 favourite, was disappointing.
Jack Naylor had previously been sighted at Roscommon on 7 July, when she won a seven-furlong maiden by three and a half lengths.
Harrington said: "She stays really well, but probably a mile would suit her better.
"She did it like I hoped she would and she loves that ground.
"She's in the Debutante (Curragh, 24 August) and I'd quite like to go there, but it might be hard with a penalty so we could supplement her for the Moyglare (Curragh, 14 September).
"You'd say she'll get a mile and a half next year what with the way she is bred."
Much-vaunted youngster John F Kennedy could finish only second on his debut in the Frank Conroy EBF Maiden.
The Ballydoyle inmate had been ante-post favourite with some firms for next season's Investec Derby, but hardly set pulses chasing as he was comprehensively beaten by Hall Of Fame as the 8-11 favourite.
Having seemed to take a long time to find his rhythm, but he was not aggressively ridden once the Jim Bolger-trained winner, who was handy from the outset, had flown at odds of 6-1.
Eddie Lynam saw Mr Snagsby's gutsy effort rewarded in the Sharon Shannon Big Band Handicap.
The 6-4 favourite set sail for home a fair way out under Wayne Lordan, and though Landau was eating up the deficit in the closing stages, Lynam's charge had half a length in hand at the line.
Mezogiorno (10-1) landed the Morocco SOREC Apprentice Handicap for trainer Mick Halford and jockey Conor Hoban, while the Korean Racing Authority Handicap went the way of Strandfield Lady (14-1) for Harry Rogers and Connor King.