took the lead approaching the final furlong and quickly opened up a clear advantage. She stayed on well to win "comfortably" by two and a quarter lengths from Hydrangea with a gap of six lengths back to Urban Fox in third place. After the race O'Brien said "We were a little confused with her run in the Moyglare. We always thought she was a little bit better than Hydrangea at home. You couldn’t be sure with them but they are two very good-looking fillies out of two very good mares." 2017: three-year-old season In 2017 Rhododendron did not contest any of the recognised trial races and made her seasonal debut in the 1000 Guineas over the Rowley Mile course at Newmarket on 7 May. Ridden by Moore she started 5/4 favourite against thirteen opponents. After being repeatedly blocked in her attempts to make progress in the last quarter mile she was switched sharply left and finished strongly but was beaten two lengths into second place by her stablemate Winter. Despite her defeat at Newmarket Rhododendron was made odds-on favourite when she was stepped up to one and a half miles for the Oaks Stakes over one and a half miles at Epsom Racecourse on 2 June. She was the only filly to offer any challenge to the winner Enable but after racing alongside the British-trained filly from two furlongs out she faded in the closing stages and was beaten five lengths into second place. She was then sent to France for the Prix de Diane at Chantilly Racecourse sixteen days later but had no chance to show her true form as she was pulled up by Moore after breaking a blood vessel. O'Brien later said "it was the worst you've ever seen. She sprayed blood everywhere. We put it down to a very hot day and she's never done it before or since but they very rarely come back from something like that." After a break of over two months the filly returned for the Matron Stakes at the Curragh in September and came home seventh of the ten runners behind her stablemate Hydrangea. At Chantilly on 1 October, faced Hydrangea again in the Group 1 Prix de l'Opéra over 2000 metres and started at odds of 11/2 in a thirteen-runner field which also included Senga, Queen's Trust (Breeders' Cup Filly & Mare Turf), Lacazar (Preis der Diana), Wuheida, Shamreen