Parker had been eyeing a push at a second Queen Elizabeth Stakes crown after Nash Rawiller provided one of the most remarkable rides to victory in the 2022 edition of the race.

The son of So You Think suffered what appeared a career-ending side foreleg tendon injury soon after, only to return from a 71-week lay-off in July last year, going on to claim victories in the 7 Stakes last spring, and the Group 1 Very Ellegant Stakes just 26 days ago.

Parker said there was no more he could ask of the eight-year-old after he pulled up sore from a fourth-place run in last weekend's Ranvet Stakes at Rosehill.

"He just pulled up a little niggly and a little off on Saturday, which is what Nash (Rawiller) thought when he rode him," Parker said.

"He thought he just didn't stretch out a hundred per cent, so we got him vetted over completely and, not that he's got anything dramatic on him, he's just got a couple of little niggles there.

"From the moment he injured himself with that tendon, there was never any chance I was going to risk him, and that's the same as now.

"Any other horse you'd just give them a spell and bring them back, but there's no need to do that with him, he's got nothing to prove.

"He's taken us on a wonderful journey. There's been heartbreak, there's been everything in it, but at the end of the day he doesn't owe us anything."

While the 2022 Queen Elizabeth run - and Rawillers's legendary wide ride to beat the likes of Anamoe, Zaaki and Very Ellegant - will always be his signature win, claiming the Very Elleegant Stakes ahead of Fangirl three weeks ago is a fitting way to finish.

Dubbed a 'giant-killer' in racing circles, Think it Over retires with 14 wins from 42 starts for just short of $8.5 million prizemoney. Parker put it succinctly following his final victory, saying "he's just a giant."

"For a long time there, before he got injured, I always said he was in the top four or five weight-for-age horses in Australia," Parker said.

"He just kept proving that. I'm just grateful for the moment he walked in my stable.

"He was very well supported, especially down here in the Illawarra, they absolutely loved him. He was loved all over the place, but he touched a lot of people here.

"I know that just walking down the road, people I don't know would congratulate me on him winning another race. It's been a tremendous ride.

"You always hope [you'll get another one], but I don't think I'll ever get one to replace him. He's just been wonderful to train, it's been a pleasure."

Parker said the incredible comeback would not have been possible without the support of owner Richard Johnston.

"[Johnston's] been a pleasure to deal with the whole way through," Parker said.

"It's not easy when you're ringing them saying [their horse] has got a bowed tendon and this is what we need to do. To come back from that and just leave the calls up to me, it's been great.

"For him and I to be on the phone for a good hour this morning, both of us have just got the horse's welfare up front.

"He's got nothing to prove to anybody and he deserves to go out on a good note."