Aidan O'Brien equalled the record for the number of Group 1 wins in a season (25) after Hydrangea dug deep to claim the Filiies & Mares Stakes at Ascot.
Bobby Frankel set the record of 25 top-level victories in a single campaign back in 2003, but O'Brien is now tantalisingly close to raising the bar even higher.
Hydrangea, under Ryan Moore, held off the challenge of 7/4 favourite Bateel to get home and see O'Brien reach an incredible milestone.
Moore said: "What Aidan O'Brien has done this year is remarkable and it is a massive team effort. Everyone who looks after these horses, they put in so much time.
"The filly has been on the go all year and has got better and better. I thought she had a good chance, I just hoped the ground would be a bit better than it was. I'm delighted for Aidan."
A subsequent Frankie Dettori double in the QEII and Qipco Champion Stakes means O'Brien will have to wait until next weekend at least to break the record when he has runners at Doncaster and in Australia
The incredible achievement was also hailed by Horse Racing Ireland Chief Executive Brian Kavanagh: "Aidan O’Brien’s career has never dipped below extraordinary. His latest achievement in equalling the world record for Group 1 victories in a year is a new high and on behalf of Horse Racing Ireland I would like to extend my congratulations to him on an outstanding achievement.
"Knowing Aidan, he will be keen to deflect as much praise as possible and will rightly shine a light on his team at Ballydoyle, his owners and the horses in his yard. But this is very much a personal landmark in the career of an exceptional trainer. We have seen that in Ireland for a quarter of a century, but with this world record will come due global recognition for a brilliant Irish horseman."
In 2001, two years before Frankel set the benchmark, O’Brien had posted 23 Group 1 victories, but the late American trainer’s record stood secure for 13 years.
Having achieved a mark of 25 Group and Grade 1s, O’Brien now heads into the autumn and winter with many more chances to set a world record mark that could stand for some time.
AIDAN O'BRIEN'S GROUP ONE WINNERS IN 2017
Churchill (Qipco 2000 Guineas) Newmarket, May 6
Winter (Qipco 1000 Guineas) Newmarket, May 7
Churchill (Tattersalls Irish 2,000 Guineas) Curragh, May 27
Winter (Tattersalls Irish 1,000 Guineas) Curragh, May 28
Highland Reel (Investec Coronation Cup) Epsom, June 2
Wings Of Eagles (Investec Derby) Epsom, June 3
Highland Reel (Prince of Wales's Stakes) Ascot, June 21
Caravaggio (Commonwealth Cup) Ascot, June 23
Winter (Coronation Stakes) Ascot, June 23
Capri (Dubai Duty Free Irish Derby) Curragh, July 1
Roly Poly (Tattersalls Falmouth Stakes) Newmarket, July 14
Roly Poly (Prix Rothschild) Deauville, July 30
Winter (Qatar Nassau Stakes) Goodwood, August 3
Sioux Nation (Keeneland Phoenix Stakes) Curragh, August 13
Hydrangea (Coolmore Matron Stakes) Leopardstown, September 9
Happily (Moyglare Stud Stakes) Curragh, September 10
Order Of St George (Comer Group Irish St Leger) Curragh, September 10
Capri (William Hill St Leger) Doncaster, September 16
Clemmie (Juddmonte Cheveley Park) Newmarket, September 30
US Navy Flag (Juddmonte Middle Park) Newmarket, September 30
Happily (Prix Jean-Luc Lagardere) Chantilly, October 1
Rhododendron (Prix de l'Opera) Chantilly, October 1
Roly Poly (Sun Chariot Stakes) Newmarket, October 7
US Navy Flag (Darley Dewhurst Stakes) Newmarket, October 14
Hydrangea (Qipco British Champions Fillies & Mares Stakes) Ascot, October 21