Belardo came home best to claim Group One glory in the Al Shaqab Lockinge Stakes at Newbury.
Winner of the Dewhurst Stakes as a juvenile, Roger Varian's charge endured a largely disappointing three-year-old campaign in 2015, but did sign off with an excellent effort to fill the runner-up spot in the Queen Elizabeth II Stakes at Ascot.
The Lope De Vega colt impressed on his Doncaster return, but could only finish fourth behind Toormore at Sandown next time and was available at 8-1 on his return to the highest level.
With Godolphin pacemaker Barchan weakening a long way from home, last year's runner-up Toormore found himself in front plenty soon enough and was soon claimed by the strong-travelling mare Euro Charline under Ryan Moore.
Marco Botti's charge looked likely to collect entering the final furlong, but having ridden an ultra-patient race, Andrea Atzeni delivered Belardo with a powerful late run on the far side of the track and he got up by a length.
The Ger Lyons-trained Endless Drama ran a fantastic race to finish third on his first start since finishing second to Gleneagles in the Irish 2,000 Guineas almost a year ago.
Limato, the 3-1 favourite, travelled well for a long way but did not appear to get home on his first attempt at a mile and finished fourth.
Atzeni said: "The last time I sat on him was the Dewhurst - he's a good horse on his day and it's a pleasure to be back on him. I remember when I first sat on him as a two-year-old I told Roger he was the fastest I'd sat on
"They went quick, he half-fell out of the stalls, but that's him and he travelled brilliantly throughout the race and picked up when he got daylight.
"It's just on the easy side of good and probably at his very best he just needs a bit of cut."
He added of his renewed association this year with the Varian yard: "Roger is a great boss and we work well together, there's a great team at home and I'm very lucky to work with him."