Hydrangea has sprung a surprise to beat her illustrious stablemate Winter in the Matron Stakes at Leopardstown.

She had been put in her place four times in Group One races by Winter since beating her in the Irish 1000 Guineas Trial at the same course in April.

The pair are also regular work companions at Aidan O'Brien's Ballydoyle stable, but Winter had suffered an interrupted preparation after her fourth top level victory in the Nassau Stakes at Goodwood five weeks ago.

Another O'Brien-trained filly, Roly Poly, made the running on Saturday (Sunday AEST) with the two stable companions not far behind.

It looked as though Winter's class might prevail, but Hydrangea (20-1) would not give in for Wayne Lordan and got the verdict by a head over the even-money favourite.

"I'm delighted for the filly and I'm delighted for Wayne," O'Brien said.

"She is Winter's work partner all year.

"She was the only one of the four fillies that had not won a Group One. We felt that Winter was going to improve a bit from the run. She was carrying a little bit of a tummy, but needed to run.

"The winner will stay further. She could go for the Prix de l'Opera.

"Winter is in the Arc and the Opera is another option.