The now five-year-old sustained the injury after an autumn three-year-old campaign that saw him chase home the likes of Ellsberg and Private Eye in the Listed South Pacific Classic (1400m) and narrowly miss to Exoboom in the Group 3 Hawkesbury Guineas (1400m).
His comeback prep back in the late autumn, early winter, of this year was forgettable but a first-up win and close second-up placing have Dunn enthusiastic about what lies ahead.
"Maybe after an injury and a year off you need one prep to find yourself again,'' Dunn said.
"It was his first prep back from his tendon injury and the whole preparation was pear shaped from the get-go. We knew he was not much good on wet ground and we tried really hard to avoid it."
Dunn tried so hard to dodge the wet the gelding, who is a half-brother to Hong Kong champion Golden Sixty, was scratched four times then contested three races in a month before he was sent out again.
He returned with a fast-finishing win over 1000m at Eagle Farm at the end of October then loomed to win at Kembla Grange two weeks ago before knocking up late and finishing third behind Cuban Royale.
"Even though he was beaten it was a better run than his first-up run,'' he said.
"It sounds crazy but three weeks is almost too far between runs with him because he's such a big, hulking, Adonis, of a horse you can't keep him up fitness wise. Especially first to second-up and I think he probably just peaked at the 50m."
Next month's Magic Millions carnival on the Gold Coast is Dunn's aim with Rainbow Connection and he says the Ranvet Handicap (1200m) at Rosehill, where he was $5.50 with TAB on Friday, is an important step.
With 60.5kg on his back he's conceding 2kg or more to his opposition but Dunn said the positives are an ideal barrier (four) and simply how well the horse is going.
"The injury seems, touch wood, to be perfect at the moment and I just train him like a normal horse now,'' he said.
"The amount of work he copes with is quite incredible, he's like no other horse in my stable. There's no holding back with him now, we'll never know what he could have been but what we've seen of him so far this prep is really encouraging.
"You'd hope a horse of his shape would carry the weight, it looks his right race. He gets the right run from the gate, slots away third or fourth the fence or one off, he'll be in the finish."
Stablemate Impasse will most likely be overlooked in the Furphy Handicap (1400m) and Dunn can understand that due to the eight-year-old's unpredictable nature.
However, the $31 chance pleased Dunn with his effort in the $2m Big Dance where he finished 13th with excuses, and he'll be back in his comfort zone on Saturday.
"He's not a miler and he got stopped twice in the straight, his run was much better than it looks when you dissect it properly,'' he said.
"He's back to a more suitable distance but who knows which one turns up. We'll go back and try and ride him for luck up the fence, that's how he won the last race he's won there."