Fame And Glory had to work hard to make a winning return in the Vintage Crop Stakes at Navan.
The top-class stayer was completing a treble on the card for the Ballydoyle team when making a successful reappearance in the 14 furlong contest.
Winner of this Listed race 12 months ago, the Ascot Gold Cup hero was pressed throughout the final two furlongs by Unaccompanied.
The 5-4 favourite got home by a neck with O'Brien junior not giving the six-year-old an unduly hard race on his first outing since October.
Table Mountain made the running with Fame And Glory hot on his heels before going on a long way from home to make it a true test of stamina.
Unaccompanied and Steps To Freedom ranged alongside but Fame And Glory had the class to take his winning tally to 14 from 22 starts.
The winning rider said: "He ran quite fresh down the back. I had a nice position on the bend going away from the stands and then he changed his legs and took off a bit.
"He just got a bit tired which he was entitled to on his first run of the year."
O'Brien junior was standing in for the first time for regular pilot Jamie Spencer who is serving a three-day ban.
Fame And Glory was generally cut to 2-1 favourite from 5-2 with bookmakers for the Ascot Gold Cup on June 21.