Aidan O'Brien will saddle two horses to take on Enable in Saturday's King George VI And Queen Elizabeth Qipco Stakes at Ascot after Anthony Van Dyck was declared a non-runner.
Having won the race twice already, along with two Prix de l'Arc de Triomphes towards her prolific Group One tally, John Gosden's Enable has proved an elusive nut to crack for O'Brien - who was ready to throw everything bar the kitchen sink at the six-year-old.
However, the Ballydoyle maestro's hand was weakened less than 24 hours before the race after last year's Investec Derby hero Anthony Van Dyck returned unsatisfactory blood results, leaving just Japan and the 2019 Irish Derby winner Sovereign to take on the great mare.
"We're very happy with Japan - everything about his first two runs this season was leading into the King George," said O'Brien.
"The first day at Ascot, he got upset in the stalls and missed the break, then he got a little tired, but we were happy. We were delighted with him at Sandown (in the Eclipse) and we felt he would progress big time for it.
"Everything about his work since has been very good, and we are where we hoped he would be. He's a year older, he's had two runs, he's progressed from his first to his second -and we think he's progressed a nice bit again.
"It's a very small field, but very select. Racing is about competitive racing, that's what everyone wants to see. We always had it in our minds this would be Japan's first big target. With horses, you go minute by minute, but at the moment we are very happy."
With Japan's two runs this season coming over 10 furlongs, O'Brien is confident two furlongs further will not be an issue.
"Japan ran a great race in the Arc as a baby three-year-old when he was beaten only two and a quarter lengths by Enable," he said.
"It was all a rush last year - we made a mess of the start, and he just made the Derby.
"As for his best trip, he gets 10 furlongs very well but he looks like he gets a mile and a half too. Obviously those class mile-and-a-half horses have the speed for a mile and a quarter as well, and that's what he's got.
"We've run lots of horses against Enable but we're always trying to compete, that's what everybody loves. It's great having strong competition, so it's great Enable is there.
"The mystery of it all is what everyone wants, nobody knows what is going to happen. It should be a great race to watch.
"It will be Enable and Frankie (Dettori) and Japan and Ryan (Moore) - so it will be some spectacle. The two horses and the two lads, we're looking forward to it.
"You have to admire what Enable has done - it's great to have her in the race and it's great she's still competing. The reality is it's like one of those old matches. It's on a great track, a stiff mile and a half, so it should be great."
He added: "All the talk of team tactics has been nonsense. Everyone can see that any one of our horses can win - no matter what prices they are or who is riding - they run to compete and compete to win, that's always the way.
"It's easy for outsiders to say this, that and the other - whether they win, lose or draw and before or after - but we don't think it's good sportsmanship ever.
"When you compete you accept the result and move forward, wish the people who beat you or finished behind you well and hope you meet again. That's always been the way.
"It's all a load of nonsense really - jockeys make funny decisions in races, some keep their ground, some don't, and the next thing everyone is up in arms saying this shouldn't happen. The stewards are there to see all those things, so it's a load of nonsense."
Sovereign will require a career-best to trouble the top two,but it is never wise to rule out anything O'Brien trains.
"It's Sovereign's second run of the season, and he's come forward lovely," he said.