Flemington racecourse fell silent as Perth visitor Gatting upset the favourite Mystic Journey to win the Group One Makybe Diva Stakes.

One of the outsiders in Saturday's 1600m weight-for-age race, Gatting ($101) was handled perfectly by Jamie Kah providing the jockey her second Group One win after guiding Harlem to victory in the Australian Cup during the autumn.

Trainer Darren Mcauliffe had confidence in Gatting making his presence felt and considered him a better chance than his odds suggested.

Stalking the speed of comeback galloper Gailo Chop and Scales Of Justice, Gatting took over at the 300m mark and then held-off the $2.05 favourite Mystic Journey by three-quarters of a length with Mr Quickie ($31) flashing home to claim third place.

Mcauliffe was lost for words post-race saying the start of the new racing season had been slow, however Saturday's win certainly worth the wait.

"I've always had a lot of faith in the horse," Mcauliffe said.

"He didn't have things go his way first-up but he's got form around Arcadia Queen that we saw win in Sydney and I think we've raced Scales Of Justice a couple of times and beaten him home each time.

"Jamie rode him perfectly, following instructions to the letter, and we got it right.

"He's a good horse, we've got a Group One now, so it's fantastic."

Gatting is nominated for next month's Cox Plate at Moonee Valley and Mcauliffe is planning another two runs ahead of the $5 million race.

Next up will be the Underwood Stakes at Caulfield on September 29 ahead of the Caulfield Stakes on October 12.

Kah said it was an amazing feeling to succeed at the top level again.

"The first one didn't really sink in and I didn't have a lot of time to enjoy it," Kah said.

"The trainer said whatever he did today, he was only halfway there, so it's pretty exciting for the future."

While disappointed Mystic Journey was unable to extend her winning streak to eight and remain unbeaten at Flemington over 1600m, trainer Adam Trinder said the four-year-old was brave in defeat.

"I thought she was still fantastic," Trinder said.

"They ran really slick time obviously with the firm track today and they ran home in a good sectional.

"She presented like she was going to go on and win the race, but full credit to the winner, he was fantastic."