David Junior swept from last to first to comprehensively reverse Royal Ascot form with the luckless Ouija Board and take the Coral-Eclipse Stakes at Sandown.
The Champion Stakes and Dubai Duty Free winner suffered a rare off day just over two weeks ago when failing to fire and taking fourth behind the Ed Dunlop-trained mare in the Prince Of Wales's Stakes.
Connections held their hands up after that and offered no excuses but the four-year-old came back to his best when leading inside the final furlong and beating the strong-finishing Notnowcato (9-1) by a length and a half, with Blue Monday (8-1) a neck away in third.
Sent off the 9-4 second favourite, Jamie Spencer settled Brian Meehan's charge right out the back, tracking Ouija Board and following Christophe Soumillon through the pack after swinging for home.
But Spencer foresaw the trouble that presented itself for the 2-1 favourite and switched David Junior to the outside for a trouble-free passage.
He may have taken a while to find his stride but once hitting the front the colt pulled clear in the 10-furlong contest for a decisive success.
His victory was undoubtedly helped by the recent purchase by his connections of Royal Alchemist, who was deployed to make the running and ensure a truly-run race for David Junior, although the filly wilted in the final furlong and finished seventh.
Meehan said: "Today is a great day - he is back winning a Group One and that is what we are here for.
"He came from last and picked up really well but he is a seriously good horse.
"I think the pace probably made the difference and Michael Tebbutt set a perfect pace on the mare and it worked out well, but all credit to Mark Usher [her former trainer] and his team."
Despite his delight, Meehan was still aggrieved over mid-week rumours which had circulated speculating about the well-being of David Junior.
He added: "We are always open and answer the questions honestly so it was annoying when that happened and there was nothing wrong with the horse.
"We had one or two things during the week which we were anxious about but that is training horses - it is not a straightforward deal."
It seems likely Royal Alchemist will again be deployed as a pacemaker in David Junior's next race, but Meehan was unsure where that may be.
"The (Juddmonte) International at York is an obvious place to go next but we will stick to 10 furlongs - it is an ideal distance - and all the big races in England and Ireland are possibles," he said.
Spencer added: "First of all well done to David Sullivan and partners for having the guts to buy Royal Alchemist and also to her jockey Michael Tebbutt for setting such a lovely gallop. It made my job so easy and this fella is a little rocket.
"I was following Ouija Board throughout. She got a little bit tight in the straight but my horse picked up so quick and he idled when he got there.
"I had planned to be in fifth or sixth but I ended up at the rear and he is a horse you have to be patient with.
"Today was a different day - Ouija Board won fair and square at Ascot and we had no excuses, but today is our day."
Ouija Board's path was blocked at every crossroads and Dunlop said: "It is disappointing for her and everyone else. She has come here as a worthy favourite but hasn't been able to show what she showed at Ascot.
"She did stumble and after that she was never going to win.
"I don't know what we'll do next but we'll take her home and talk to the owners and see where we go from there."
Her French-based rider added: "The pace was very fast. I had enough pressure from the outside to worry me and I didn't want to push my filly for her run too soon.
"The horse on my outside (Aussie Rules) kept keeping me in and it was very difficult on this track to find any room. I decided to switch her inside but she stumbled for a stride, only to stay on again at the end."
Roger Charlton was thrilled with the effort of Blue Monday.
"There were a few doubters about our decision to run, saying he was just a handicapper. He had to switch right around them but was staying on encouragingly up the hill," he said.
Owner Martin Myers added: "I am an ambitious owner and I think the extra half furlong of the Juddmonte International would suit him."
The Ballydoyle outfit arrived at Sandown looking for a much-needed tonic following the events surrounding stable jockey Kieren Fallon this week.
With the six-times champion unable to ride due to a ban from the Horseracing Regulatory Authority and substitute partner Johnny Murtagh injured, Alan Munro took the ride on fourth-placed Aussie Rules.
He said: "When he went to the front I thought he was going to win. He was headed straight away but he continued to fight and seems a very genuine horse."