Rhododendron led home Hydrangea to provide Aidan O'Brien with a one-two in the Group 1 Dubai Fillies' Mile at Newmarket.
This victory brings the trainer within six of the world record for training Group/Grade 1 horses in a year of 25, set by the legendary US trainer, Bobby Frankel.
Rhododendron had narrowly beaten her stable companion when landing the Debutante Stakes at the Curragh in August.
But that form was reversed in last month's Moyglare Stud Stakes, with Hydrangea second and Rhododendron third behind the Joseph O'Brien-trained Intricately.
The pair locked horns again on the Rowley Mile and with Ryan Moore opting to ride Rhododendron, she was the heavily-supported 5-2 joint-favourite along with Godolphin's Sobetsu.
Spatial took the field along for a long way, but Rhododendron made ground quickly once let down and quickened up to lead heading inside the final two furlongs.
Hydrangea did her best to make a race of it, but was ultimately no match for the winner, who came home with two and a quarter lengths in hand.
Hydrangea was another six lengths clear of 40-1 shot Urban Fox in third, with Sobetsu very disappointing.
Moore said: "She travelled beautifully into the race. She's won very easily. She's done that with a real lot of class.
"The last time I rode her was at Goodwood, she impressed me that day.
"She was disappointing the last day - she hung a bit - but she's back to her best.
"She's an awful lot of class."
O'Brien said of the winner: "She's a very good filly. She's a filly that's really progressed."
O'Brien managed 24 Group/Grade 1 wins in 2001 and should close in on Frankel's record in the next few weeks: he has the favourite, Churchill, in the Dewhurst Stakes at Newmarket tomorrow, as well as a number of big international meetings coming up between now and December.