Aim stunned punters but not co-trainer Paul Snowden when he scored a boilover win in a dramatic Magic Millions Guineas (1400m) at the Gold Coast on Saturday.

Overlooked by most punters, Aim ($31) powered clear to win the Guineas by 1-3/4 lengths from Amish Boy ($31) with Away Game ($4.60) 3/4 length away third.

The heavily-backed $2.15 favourite Isotope stumbled and dislodged jockey Ryan Maloney early in the home straight before galloping on unharmed past the winning post.

Maloney was lucky to escape serious injury but was stood down from his remaining rides on the program and was taken to hospital for precautionary tests.

Snowden was confident Aim could regain his best form on a dry track in the Guineas after failing in the wet first-up in midweek grade in Sydney.

"He just needed to get back on firm going and we just had to bite our tongue and run him a fortnight ago to get him started," Snowden said.

"Knowing the horse he just doesn't let down and he ran accordingly that day."

The Star Witness gelding started favourite in last year's Magic Millions 2YO Classic but could manage only eighth to Away Game.

"He lost his way a wee bit after that two-year-old season but he's back as a gelding this preparation and it's been the making of him," Snowden said.

"He's a lot stronger now but that comes with maturity as well."

Aim was expected to be sold to Hong Kong earlier this season but the sale fell through.

"The money didn't come through so we just played on and look what we've got today," Snowden said.

"Thankfully we've got him back and who knows what can happen from here."

Winning jockey James McDonald eased Aim back to second last before circling the field on the home turn and hitting the line inside the 200-metre mark.

"About the 500 metres I thought 'stuff it' so I sent him forward and to his credit he stayed on well," McDonald said.

"It's been a very frustrating day but it's good to get that one anyway."

Aim is the second Guineas winner for McDonald who rode Sweet Idea to success in 2014 and the first for the Snowdens.