"We were pretty confident he was in the [Cup] field after the Bart Cummings."
On October 5, jockey Glen Boss took Who Shot Thebarman away from the field in the group three 2520m race at Flemington, adding to his last-start win at Australia's racing headquarters over 2000m, winning by two-and-a-half lengths.
That victory was the eighth from 14 starts, earning a spot in the A$3m Caulfield Cup (2400m) on October 18, while being a prospect for the Melbourne Cup final field if a penalty for weight could be gained from race handicapper Greg Carpenter.
Unfortunately, the next step was not as successful as Who Shot Thebarman was disappointing in the Caulfield Cup, running 13th with Boss, while Japan's Admire Rakti produced a powerful sprint to win the race from Kiwi mare Rising Romance, with the favourite Lucia Valentina in third.
Before the race, Waller had said their horse would want to be in the top three or close to it to be a prospect in the Melbourne Cup.
"Caulfield was a real hiccup," said Dan O'Leary yesterday.
"But he shouldn't have even gone in the race, he was ridden upside down and it wasn't his track.
"He had a lot of excuses, so [we] forget that and move on.
"He's trained at Flemington and we think he's a good chance."
Japan raider Admire Rakti will start as the $5 hot favourite after his connections again drew barrier eight for the Melbourne Cup race, the same as their jump for the Caulfield.
"It is a lucky number," said trainer Tomoyuki Umeda.
"There is no change in the horse and he is just as good as he was before the last run. He has had the one gallop since, he is still good."
Waller has guided seven group one winners this season, but has yet to claim one of Australia's big four - Melbourne Cup, Caulfield, the Golden Slipper, or the Cox Plate.
He has also trained Junoob ($21) and Sydney Cup runner-up Opinion ($51) in tomorrow's field.
"If I keep getting my horses ready the right way a major will come," he said, as Who Shot Thebarman has been raced lightly with the Cup in mind.
"I don't know if it will be on Tuesday or in 10 years - I just do my best and let the horses show their best."
Likewise, Boss is being realistic but if anyone knows how to win the Cup then it is this Sydney jockey.
Boss's legacy was secured when he rode Makybe Diva to all three of her 2003-5 Melbourne Cup wins.
"I don't know if he's got the class to win the Cup, but his two wins at Flemington were very good, and he'll love the two miles," Boss said last week.
The O'Leary brothers plan for Tuesday is to head to Flemington a little later in the day, after the first race, and then stay close to their horse in the tie-down area.
Then they will be escorted to the owners enclosure for the 5pm Australian start time of the "race that stops a nation".
"And after that? Well, we'll see what happens after that," said Dan O'Leary, referring either to rejoining the public gallery or perhaps making that trip to the winners circle.
Who Shot Thebarman was named after a favourite saying of the O'Leary's aunt when her gin glass was empty and needed a refill.