Trainer Jean-Claude Rouget said of his 5-2 favourite: "I hope now she's in a good place for the rest of the season".
Last year, three runners made their way to Sha Tin after competing at Royal Ascot, including the victor Defrocked, now known as Limitless, third-placegetter Chief Whip (renamed California Whip) and the horse who finished sixth, Out And About (now Booming Delight).
"I've got to give it to Jamie", Ward said, "I don't want to tell you all the frightful names I was calling him in the first part of the race".
O'Brien - who until Tuesday had carried nearly all before him this season in winning three of the four English classics - said Churchill had run a good race, but jockey Ryan Moore was perplexed. Back on good ground, he won the Coronation Cup (G1) at Epsom in preparation for Royal Ascot. "I'd say it was probably a career-best from him today". "From that day we have moved forward and we are really enjoying it".
Highland Reel is teak tough, however, and he held off that pair by a length and a quarter.
Edita Ligere poses for photographers wearing a large feathered hat on the first day of the Royal Ascot horse race meeting in Ascot, England, Tuesday, June 20, 2017.
Kate and William were pictured with Prince Edward and his wife Sophie, Countess of Wessex as they arrived in the Parade Ring for the event, and the weather was on their side as temperatures hit 31°C.
The Britannia Stakes is one contest local punters should play close attention to with the 1,600m race regularly raided by bloodstock agents looking for a potential Hong Kong Derby horse.
Earlier, O'Brien said he is keen to assess Churchill's well-being within the next fortnight before he firms up plans for the dual Classic victor.
Godolphin won three races on the opening day, including the St. James's Palace Stakes with 5-2 shot Barney Roy as favorite Churchill finished fourth in the signature race.
The biggest win in Fahey's career, he signalled next month's Sussex Stakes at Glorious Goodwood as the next assignment for the champion miler who, at the age of four, is now maturing into the complete racehorse.
O'Brien said: "He seems to be fine but he didn't eat up his full dinner last night, which is a bit unusual as that was the only thing that was different".
"He might go for the Eclipse but we'll talk to the owners".