Washington DC (11-4 favourite) finally won his first Group race when just getting the better of stablemate Cougar Mountain in the At The Races Phoenix Sprint Stakes.
A sprinter who has danced every dance in recent seasons, he has regularly come up short against the best but he was a Listed winner early in the season.
Gordon Lord Byron was in there fighting as usual, but Cougar Mountain swept by him only for Washington DC to pounce and give Moore a treble having also won the feature Phoenix Stakes on Sioux Nation.
"He has a load of ability. He has loads of speed for five, but it's just a little bit hard to produce him over five," said O'Brien.
"Over six he has a little bit more time to produce him and wangle him through. He just doesn't want to be in front very long.
"He's the type of horse we'll have to turn up (everywhere) as he can be unlucky in a race. He loves coming through horses. I wouldn't be ruling York (Nunthorpe) out or Haydock (Sprint Cup) after that."
On the runner-up, he added: "Donnacha (O'Brien) said to go back to six with the horse as you're stretching him out too much.
"He had some very good runs over six and was only beaten three lengths in the July Cup on only his second run.
"He has plenty of speed and is another horse that things just have to fall for him. If we could go back to that it would be a lot easier for him."