[4] Rey de Oro made his debut in a contest for previously unraced two-year-olds over 2000 metres at Tokyo Racecourse on 9 October and won by a length.

He was made the 4.3/1 second favourite behind the Aoba Sho winner Admirable while the others included Suave Richard, Al Ain, Satono Arthur, Persian Knight, Danburite and Clincher.

"[8] After a summer break, Rey de Oro returned for the Grade 2 Kobe Shimbun Hai (a trial race for the Kikuka Sho) over 2400 metres at Hanshin Racecourse.

[9] On 26 November Rey de Oro was matched against top class older horses to contest the Japan Cup over 2400 metres at Tokyo and started 2.8/1 second favourite behind the five-year-old Kitasan Black.

He was then sent to the United Arab Emirates to contest the Sheema Classic on 31 March and stayed on in the straight to come home fourth of the ten runners behind Hawkbill, Poet's Word and Cloth of Stars.

[13] Five weeks later, with Lemaire in the saddle, the colt started the 2.1/1 second favourite behind Suave Richard for the autumn edition of the Grade 1 Tenno Sho over 2000 metres at Tokyo.

After racing in sixth place, Rey de Oro moved into contention on the outside on the final turn before taking the lead from the front-running Kiseki in the straight.

[15] As Lemaire had been booked to ride the filly Almond Eye in the Japan Cup, Rey de Oro's connections opted to bypass the race in favour of the Arima Kinen.

The field is partly determined by a public vote and Rey de Oro stopped the poll ahead of the absent Almond Eye and the popular steeplechaser Oju Chosan.

[18] In March 2019 Rey de Oro was again sent to Dubai for the Sheema Classic, but after leading for most of the way he faded badly in the straight and finished sixth of the eight runners, more than twelve lengths behind the winner Old Persian.

He raced on the inside in sixth place but was unable to make any significant progress in the straight and came home fifth behind Lys Gracieux, Kiseki, Suave Richard and Al Ain.

Despite having failed to win in over a year, Rey de Oro started the 3.2/1 favourite for the Japan Cup on 24 November but came home eleventh of the fifteen runners behind Suave Richard.