Rock On Wood, who won the Captain Cook on this track and over this distance last month, could have a fitness edge having been luckless in the Zabeel Classic at Ellerslie five weeks ago, but Bosson, who is back from suspension, is adamant Melody Belle is ready after she tested his strength in a private workout on Thursday.
"With her, you know how ready she is by her trackwork," Bosson told the Herald.
"On Thursday, she worked 1200m and we were supposed to let her run up a bit more the last 400m, but when we got there, she was just charging and I could barely hold her.
"That is a really good sign because over her career, when she has been like that, she has raced at her best."
Melody Belle's best would be too good for he rivals and Bosson said he was happy with barrier one.
"I always like barrier one," he said with a smile.
"I will ride her where she is comfortable but there could be a couple of leaders there to follow, and if they go a good speed, the gaps should come."
The Mitigator, Deerfield and Shadows Cast are all freegoers who should be up on the speed, and Melody Belle should be able to track them, with perhaps her greatest threat, Rock On Wood, able to get outside her and pocket her and hold up Melody Belle's momentum at a crucial stage.
But she is a big strong mare with New Zealand's best jockey on board on a roomy track in a small field, so if you're backing Rock On Wood to beat Melody Belle by out-manoeuvring her, you might be hoping for a miracle.
If Melody Belle can equal Sunline's record, it will outshine the Wellington Cup, which for all its historical significance is still a Group 3 race these days.
Saturday's version does at least boast plenty of genuine stayers, so sets up as a 3200m test, with Waisake a deserved favourite carrying just 53kg.
Melody Belle's trainer Jamie Richards could have one of the blowout chances in the race, though, in Te Akau Caliburn, whose last-start run in the City Of Auckland Cup suggests he can test the locals.
Best bet: Melody Belle (R7, No 3): Champion NZ mare ready to equal Sunline's record and gets 1kg from Rock On Wood. Take the shorts.
Each way: Son Of Bielski (R8, No 4): Taken on at Ellerslie last start but fought well. Look to be ridden differently here and drops in class.
Go again: Lincoln Falls (R10, No 3): Nothing went right last start but this field is not strong and big track suits. Last time he raced here, he ran fifth in the Levin Classic.