When it comes to Bart Cummings's best horses of the modern era, the legendary trainer's long-serving Melbourne foreman Reg Fleming never thought he'd deal with another as good as Saintly.

The striking chestnut's career was cruelly cut short midway through his four-year-old season, after just 23 starts, but not before he won a Melbourne Cup, Cox Plate and Australian Cup as a three-year-old, the last youngster to do so.

So for Fleming, who has been Cummings's right-hand man for 15 years, to mention So You Think in the same breath as Saintly suggests the son of High Chaparral is truly one out of the box.

"Saintly's on a pedestal by his own in my opinion, but this horse is going the right way (to match him)," Fleming said. "He's pretty good and I'm glad to have him."

The four-year-old is building a career that, if it continues, will see him remembered the best horse since 1980's champion Kingston Town, an inaugural Hall of Fame inductee.

On Saturday, he won the Group One Yalumba Stakes at Caulfield and if he takes out his second Tatts Cox Plate on October 23 - he is already as short as $1.65 to do so with some bookmakers - he will become the first Cox Plate-winning three-year-old to follow up victory at four.

The most remarkable part of all about that is that he will still have had only 10 starts!

To put that into perspective, Sunline and Northerly - the only other back-to-back Cox Plate winners since Kingston Town won the last of his three-straight titles in 1982 - didn't win their first Cox Plates until starts 18 and 16 respectively.

Melbourne Cup legend Makybe Diva won the 2005 Cox Plate and was unbeaten in our most famous race, but she didn't demonstrate an ability to beat the best at weight-for-age stars until the final year of her career.

Better Loosen Up, Saintly and Might And Power are other Cox Plate winners who have been Australia's best horse at some stage in the past two decades, but none of them have been as dominant so early in their career as So You Think.

It's been a remarkable rise to prominence considering he kicked off his career in a midweek no-metro-wins two-year-old race at Rosehill. He won at the amazing price of $6.

Cummings then gave him three and a half months off before stepping him out in the listed Ming Dynasty Stakes, in which he finished a narrow second, before winning the Group 3 Gloaming Stakes.

The only unplaced run of his career came next up, in the Caulfield Guineas, when he never really got a crack at them after being ridden back in the field off what was a slow tempo.

Since then he has been almost unstoppable. Last year's Cox Plate romp was followed by an Emirates Stakes second on the last day of the Melbourne Cup Carnival when Cummings wasn't impressed with Glen Boss's aggressive ride.

He missed the summer/autumn carnival after encountering some throat issues, but they haven't stopped him waltzing through the spring so far undefeated.

After resuming with victory over Whobegotyou, Shoot Out and Typhoon Tracy in the Group 2 Memsie Stakes on August 28, he logged back-to-back Group 1 wins in the Underwood Stakes on September 18 and Saturday's Yalumba Stakes.

It made him the first horse since Lord in 1960 to win the Memsie-Underwood-Yalumba treble in the same spring. Ajax, in 1938, is the only horse to win those three races and the Cox Plate in the same campaign.

Saturday's success was one of the most dominant Group 1 wins in Victoria since Sunline's seven-length romp in her second Cox Plate win. He was five lengths clear with 50m to go, but coasted in by three-and-a-quarter lengths after being eased down by jockey Steven Arnold.

Those questioning whether So You Think should yet be ranked alongside Makybe Diva, Sunline, Northerly and Might And Power as greats of the modern era will point to the fact that Alcopop - who is yet to reach the heights of last spring - finished second on Saturday, but Whobegotyou did run third.

"Whobe", remember, won last year's Yalumba as a $2.15 favourite and was all the rage in last year's Cox Plate.

Arnold makes no secret of how honoured he is to be associated with So You Think.

"He's just a magnificent horse, I wipe my feet before I get on him," Arnold said. "He's first class and it's a pleasure to ride him."

Who knows what Cummings will do after the Cox Plate with So You Think, but a crack at emulating Saintly and winning the Cox Plate-Melbourne Cup double in the 150th edition of the race in which Cummings has made his name should prove irresistible.

Perhaps that's when the baton will officially be handed over in Fleming's eyes.