Gai Waterhouse captured the biggest prize of the Melbourne spring carnival but her Melbourne Cup win with Fiorente was just one of many highlights.

Chris Waller and Robert Heathcote dominate racing in their home states and showed why with three Group One wins apiece during the Melbourne spring carnival to head the trainers' leaderboard.

Waller is Sydney's premier trainer and Heathcote holds sway in Brisbane and while both have had success in Melbourne before, they upped the ante this time around.

The Heathcote-trained Solzhenitsyn did what he had done a year earlier by winning the Toorak Handicap but it was Buffering's two Group One sprint wins that brought the most joy.

Buffering has been Queensland's Horse of the Year for the past two seasons despite not winning a Group One race in 17 attempts before the Manikato Stakes.

Under lights at Moonee Valley in the absence of old adversaries Black Caviar and Hay List, Buffering stepped out of the shadows and showed it was no fluke at Flemington on the final day of the carnival when he dominated the VRC Sprint Classic.

"I always said would be at his best at six," Heathcote said.

"I'm also very happy Black Caviar and Hay List have retired.

"I'm fortunate to have a horse like Buffering. He's a unique little animal."

Zoustar gave Waller his first Group One of the Melbourne carnival, a win that came with a certain amount of pressure.

In the days leading up to the Coolmore Stud Stakes, a multi million dollar deal was struck between the Golden Rose winner's owners and Widden Stud, with bonuses for a second Group One.

He duly delivered under a masterful ride from Jim Cassidy, a win that gave the popular jockey his 100th at the highest level.

Since he came to Australia's attention winning the 1983 Melbourne Cup on Kiwi as a fresh faced 20-year-old from New Zealand, Cassidy has had a career that has reached the highest highs and some pretty deep lows.

But he has bounced back from controversy and injury and says that at 50, he has no thoughts of retirement.

Red Tracer, a six-year-old mare who never gives up, gave Waller his second Group One in the Myer Classic while stablemate Boban, a restricted class galloper in the autumn, rose to the occasion to win the final Group One, the Emirates Stakes.

Boban was ridden by Glyn Schofield, an international rider for many years before settling in Sydney with his family.

And for Schofield, while he savoured the win, it did not compare with the sheer elation of watching his apprentice son Chad ride the race of his life so far to win the Cox Plate on three-year-old Shamus Award.

"I've never been so emotional after a race as I was when Chad won the Cox Plate," Schofield said.

Damien Oliver, who returned in the spring after 10 months on the outer for a betting offence, rode Fiorente to win the Cup, replacing the sacked Nash Rawiller.

But Rawiller still managed to top the jockeys' list with Group One wins on Solzhenitsyn, Red Tracer and Kirramosa, winner of the Oaks.

The Melbourne Cup may have been Fiorente's last under handicap conditions with Waterhouse and the horse's many owners weighing up options both here and overseas.

But Australia's weight-for-age championship, the Cox Plate, seems a likely target.

Before she won the Melbourne Cup, Waterhouse had trained three second placegetters in the race.

Her Cox Plate record is two seconds - Lotteria (2005) and Manhattan Rain (2009 - and two thirds - Pierro (2012) and Fiorente (2013).

With five Golden Slippers, a Caulfield Cup and now a Melbourne Cup, Waterhouse needs just the Cox Plate to complete the grand slam.

That may come in 12 months time.