He has won a Caulfield Cup with Southern Speed, a Victoria Derby with Rebel Raider and two Toorak Handicaps with Umrum, but Leon MacDonald rates filly Go Indy Go their equal after her barnstorming Champagne Stakes victory.

The experienced horseman held the youngster in high regard prior to Saturday's Group One race, but wasn't prepared to publicly declare his admiration until she proved herself on the racetrack.

Go Indy Go ($7) produced an electric sprint to come from last on the turn and win the 1600m contest by a length over Zululand ($17), which fought back well after racing on the speed.

Kumaon ($16) represented Peter Snowden's final Group One runner for Darley and finished third, another short head away.

"She beat nothing the other day at Morphettville, but it was a track gallop for her," MacDonald said.

"We knew she had a lot of ability and she'd worked really well leading into the race.

"I didn't like to say it before the race, but I think she rates up there with the best of them on what she's shown me.

"When you've had a Gold Guru and a Rebel Raider, and an Umrum and a Southern Speed, and Serious Speed won a Thousand Guineas and a Hobartville, I think she rates right up there."

Go Indy Go was ridden by Chad Schofield and gave the young rider his third major of the season after a Cox Plate win aboard Shamus Award and Newmarket Handicap success on Lankan Rupee.

He was in awe of the ease of Go Indy Go's win.

"On the turn (favourite) Peggy Jean whipped around me and as soon as it did that I hopped on her back," Schofield said.

"As soon as I balanced her up in the straight and asked her to quicken she did exactly that and put a good field away very easily.

"It was an incredibly dominant win."

Gerald Ryan started three horses in the race including Peggy Jean, which did the best of the trio to finish fifth.

He said the filly had come to the end of her campaign and also questioned whether she ran a genuine mile.

He was disappointed with Bachman, which was ninth, while Lucky Raquie (tenth) again failed to handle a rain-affected track.

Fillies have won all four Group One two-year-old races this season with Earthquake claiming the Blue Diamond Stakes, Mossfun the Golden Slipper and Peggy Jean the Sires' Produce.