The Queen tested positive for COVID-19 Feb. 20 but was given a welcome reason to smile when exciting prospect Kincardine justified odds-on favoritism in the 2 1/16-mile maiden hurdle at Newbury.
Buckingham Palace confirmed the positive test and said the monarch was experiencing "mild cold-like symptoms" but that the 95-year-old expects to continue with her "light duties" at Windsor next week.
Trained by Nicky Henderson, Kincardine was sent off at 4-6 and made all to beat Super Duper Sam by 4 1/2 lengths.
The 5-year-old, who was also bred by the Queen, won a bumper at Southwell on his debut in May and was third behind Ballymore Novices' Hurdle contender Stage Star at Newbury in November.
"I hope the winner puts a smile on Her Majesty's face and I do hope she's not feeling too bad," said Henderson. "I believe Kincardine has a bright future and he should make a nice chaser in a year's time.
"He'll want three miles and he's done well to win over this distance. He's not a two-miler but in these conditions you've got to stay well."
Speaking to Racing TV following Kincardine's breakthrough victory over hurdles, the trainer added: "We're all sad to hear Her Majesty has COVID. I don't know if that's COVID medicine but I hope it is.
"We always knew it was going to be tough and I didn't really want to come back to two miles with him. There was a pretty competitive race at Ascot on Saturday over 2 1/2 miles, which looked nice and was an option, but we decided to go for this maiden.
"In this ground it was far enough for him. It was hard work but he enjoyed it and handled it well. This is only practice and he should make a three-mile chaser. I hope he might be a rather smart one."
The Queen has celebrated three winners from 17 runners over jumps this season, having also struck with Rapid Flight in May.
Her biggest successes have come on the flat and she landed six pattern races last year, most notably the Betway Solario Stakes (G3) with Reach For The Moon and the William Hill Summer Stakes (G3) with Light Refrain .