Leading Light made a successful reappearance when running out a workmanlike winner of the Coolmore Vintage Crop Stakes at Navan.
The Ladbrokes St Leger hero was running for the first time since finishing down the field in the Arc at Longchamp in October and took closer order behind the front-running Royal Diamond with a half a mile to run.
With the latter sticking to the far rail, Joseph O'Brien's mount came down the middle in company with Pale Mimosa, and the even-money favourite loomed large two furlongs out.
When asked Leading Light responded sweetly and went nicely clear in the final 200 yards to win with three lengths in hand from Royal Diamond, who kept on well to take second.
Winning trainer Aidan O'Brien said: "You'd have to be very happy with him, you couldn't be happier really. I was very happy with him at home, he's a lot stronger and was doing all the right things. He had the penalty there for his first run and it was a proper run race.
"We haven't seen the bottom of him yet, at the end of two miles at Ascot last year (Queen's Vase) he didn't seem to be stopping so we will look forward to that (Gold Cup) and he could run in the Saval Beg before that.
"When he gets there (to the front) he pulls up so that's why he wears cheekpieces. It was lovely that they went a gallop and he could take his time and didn't have to make his own running. He settled well, travelled well and quickened twice down the straight."
Sky Bet cut the winner to 2/1 for the Royal Ascot contest, spokesman Michael Shinners saying: "This has been the race Aidan O'Brien has targeted with his Gold Cup horses and the 2014 winners looks a huge player next month."
O'Brien doubled up when Leading Light's full-brother John Constable (5-4 favourite) stayed on strongly in the Excelebration Maiden.
The three-year-old was getting off the mark at the sixth time of asking, beating Karezak by three-quarters of a length.
Like his brother last year, he could be aimed at the Queen's Vase at the Royal meeting.
O'Brien said: "We might have run him a bit short the first couple of times. He only ran over seven furlongs twice as a two-year-old. When we stepped him up to a mile and two it appeared to help. The Queen's Vase at Royal Ascot could be an option now."