Trained by William Muir and Chris Grassick, the four-year-old landed the Coronation Cup at Epsom last time out.
He had been among the leading fancies for the midsummer showpiece but a minor setback will prevent him from lining up.
Muir told Nick Luck’s Daily Podcast: “He worked superb on Saturday, we went to Charlie Hills’ and he worked stunning with a very good miler.
“I walked over to meet him coming back – he was bouncing – washed him down and what have you and all was fine, but that evening I just thought he was slightly wrong behind on his off hind.
“My vet came, his testicle was pulled right up so he thinks he might have rolled in his box and tweaked his groin.”
Later, speaking to the media in Lambourn this morning, Muir said: “We did exactly the same as before the Coronation Cup; we went over to Charlie’s [Hills] gallops and Martin [Dwyer] rode him, he was delighted with him, he went magnificently. It was not a hard piece of work, but the way he came through it was fantastic. I walked off the gallops thinking, ‘It will take a good horse to stop this’.
“I walked across to meet him coming across the road, he was bouncing and bobbing and kicking, I thought then this horse has never been better, I couldn’t have him better. Martin came back and said, ‘He is in such a good place’.
“He was washed down, put in the box, he had a roll, everything was fine, he never took a funny step anywhere, then in the evening my head girl rung me, I was at Newbury races, and said, ‘Pyledriver is just not quite right on his off hind’.
“My vet came out while I was still at Newbury, and he felt that he was sore up in the groin area and we were thinking could he have pulled his groin? The vet then came out again on Sunday morning and there is obviously pain there.
“We are hoping it is a groin injury, but we are going to make sure we don’t leave any stone unturned. So we will X-ray his tibia, if there is nothing there, we will scan his pelvis, I don’t think it is, but it will put my mind at rest. Then we can go from there and will know it is soft tissue.
“You can’t have any setback to win a Group 1, in fact, forget Pyledriver, if there is any setback, even if it is the lowest-rated horse in the yard, I won’t run the horse if there is any doubt in my mind.
“I am not going to put the horse under pressure. If it is something simple, and we will know in three days, we will wait and go to the Juddmonte International.
“If it is something that we need to give him four to five weeks, then he will have his break and go to some of those races at the end of season [the Arc, the Breeders’ Cup, the Japan Cup], there are so many options.
“The worst thing is if you don’t take notice of what you’ve got now then all of a sudden you’ve got a serious problem. I can’t take any chances with any horse. I am always cautious, more than anything else. It is very slight and he has never taken a lame step in his life. I am gutted to be honest.
“I know Love is very good, but she might have fallen in love with Pyledriver after Saturday! I’d have taken anything on. When he came off the gallops, I promise you I thought, ‘Whatever beats him will win’.
“I thought he’d win it, to be honest, I really did. I know they are great horses, the Derby winner is a very good horse, probably one of the best; I am not even going to be part of it anymore, it is tough.
“I have never been so excited about a race, Saturday morning I was doing somersaults coming off the gallops. That evening it was just a strain driving back from Newbury, have I slept since? Not really.
“It looks a fantastic race. Love is a great filly. The Derby winner was mightily impressive, but the ground is going to be different than Epsom; the ground wouldn’t have worried me.
“We have had a great run with him, not just this year, as a two-year-old, three-year-old and now. We will return. He will stay in training next year – we can go back for the King George next year!”
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