The Ballydoyle maestro has spoke out about entering Japan, one of his stars of the season, into the Group 1 Juddmonte International at York at the Ebor meeting next week where he could give his trainer his sixth win in the black type event.
The Epsom Derby third looked very unlikely to run at all at York but to now be considered for the Juddmonte International which would see Japan drop to 10 furlongs which would be a strange move with his best performances coming over further.
He is currently the 3/1 favourite to take the St Leger at Doncaster in September with many thinking this was the main plan but with O'Brien being elusive as ever with his horses the three year old has to be looked at in the Juddmonte market.
The son of Galileo has had a stellar season to date making his seasonal debut in the Dante Stakes finishing a staying on fourth but it was a race to really get him fully fit for the Epsom Derby.
He went to the prestigious track and was a neck away from taking the glory but had to settle for third in a three way photo finish but it was refreshing to see him start to live up to his pricey purchase.
In his last two runs he has been a horse to reckoned with winning at Royal Ascot in the Group 2 King Edward VII Stakes and then landing his first Group 1 of the season over in France in the Grand Prix de Paris at Longchamp.
(Credit Racing Post) O'Brien said: "Japan is in good form since his run in France. Everything has gone smoothly with him since then and he is definitely in the mix for York, along with a few others. We have always thought he was a lovely horse and he is progressing nicely this season."
O'Brien as ever holds multiple entries in the Group 1 contest and could field Magical who is set to go off at a small price and St James's Palace Stakes winner Circus Maximus is also in the mix at a single figure price.
The Irish trainer last won the race in 2014 with Australia and hopes that he can get back to winning ways this season in this feature contest.
He added: They are all in the mix. Magical is in good form. Circus Maximus is very consistent and seems in good form too. We will decide closer to the time and nothing has been decided yet."