Kew Gardens led home a one-two-three for Aidan O'Brien as he dominated the Queen's Vase to gain a first winner of the week at Royal Ascot.
Only ninth in the Derby when last seen, the 100-30 winner was the choice of Ryan Moore and ultimately ran out a decisive victor.
Despite racing over the extended mile and three-quarters distance for the first time, Nelson set a very stiff gallop at the head of affairs.
Turning into the straight he was still in front, but the pack was closing, including Frankie Dettori on Stream Of Stars.
It soon turned into a Ballydoyle benefit, though, with Kew Gardens sprinting clear and Southern France coming from almost last to beat Nelson for second, some four and a half lengths away.
Kew Gardens is now as low as 10-1 for the St Leger, a race connections appear keen to go for.
Michael Tabor, co-owner of the winner, said: "We've always thought he's a nice horse, really made for this race. Obviously he needs a trip, so the St Leger, why not?"
O'Brien said: "We always thought he'd stay. He loves fast ground. He was a little bit disappointing in Epsom, but we've been very happy since then.
"He can do a lot of things. He can go back to the Irish Derby. He can have a little break and be trained for the Leger. He's a lot of options.
"The Leger is a long way away, but in the autumn that would be a lovely race for him."
He added: "You'd be very happy with them, and they are all horses for the future really."
Best of the rest in fourth was the John Gosden-trained Almoghared, who could also be Leger-bound at Doncaster in September.
Michael Stoute became the winning-most trainer in Royal Ascot history when Poet's Word claimed victory in the Group 1 Prince of Wales's Stakes.
The Newmarket great is now out on his own with 76 triumphs at the Royal fixture - one ahead of the late Henry Cecil - after the 11-2 chance defeated hot favourite Cracksman by two and a quarter lengths.
Stoute said: "It's a relief because we were stuck on it (75 winners) last year. It (Royal Ascot) is special to every trainer.
"We've been very lucky to have a lot of nice horses over the years."
Cracksman never showed his best form throughout the Group One over a mile and a quarter, whereas Poet's Word was bright and alert under James Doyle and won handsomely.
Aljazzi went one better than 12 months ago when routing the opposition in the Duke of Cambridge Stakes.
A surprise second to Qemah last year, Marco Botti had plotted the first half of the season around a return to this Group Two contest.
Sent off the 9-2 second-favourite behind the Aidan O'Brien-trained Hydrangea, William Buick was content to settle his mount at the back of the pack.
Billesdon Bess was allowed an easy lead and was still in front a furlong and a half out when Tribute Act shot to the head of affairs.
But as soon as Buick found open space on Aljazzi (9-2), the race was over and she burst clear.
Tribute Act was at the head of the chasing pack in second, with Epsom winner Wilamina a fine third.
Hydrangea was a big disappointment and was one of the first beaten.
Signora Cabello narrowly prevailed in a blanket three-way finish to the Queen Mary Stakes at Royal Ascot.
A big-priced winner of a Listed race at York last time out, the powerful Phoenix Thoroughbred organisation bought a three-quarter share into the filly.
Still in the care of John Quinn and ridden by Oisin Murphy, the daughter of Camacho was sent off at 25-1 on this occasion, and was never far from the pace.
Aidan O'Brien's Gossamer Wings and the Clive Cox-trained Shades Of Blue were late challengers, but it was the northern raider who prevailed by a short head and the same.
Wesley Ward's favourite Chelsea Cloisters never threatened at any stage under Frankie Dettori.