The winner of her first five starts, including the Group 1 New Zealand 1000 Guineas (1600m), Legarto was defeated for the first time when fourth behind Prowess in the Karaka Million 3YO Classic (1600m) when enduring a troubled run from an inside draw.
New Zealand's wet summer has forced Kelso's hand to trial on the synthetic track at Cambridge this week, with Avondale's turf trials postponed a week.
“I have no option but to trial on the synthetic but she has trialled there previously as a two-year-old,” Kelso said.
“She had a few days off after the Karaka Million and has been working up since. As long as she has a nice hitout and is finding the line okay I will be happy.
“She will have a trial and we also have the option of an exhibition gallop at Matamata plus a trip to Aussie so we won't be far away.”
Rated an +700 chance for the Australian Guineas, Legarto will now clash with boom colt Jacquinot (+320), who won the Group 1 CF Orr Stakes (1400m) on protest against the older horses on Saturday.
“He is the horse to beat for sure but it's hard to measure them up,” Kelso said.
“I think she's got a lot of ability and she deserves a crack at it.
“She's won her Group One in New Zealand, so if she could run top three over there, it would greatly advance her value.
“We're pleased to book Michael as he's riding in great form and he's ridden well for us in the past on Levante.”
Dee is enjoying his best season in Australia after moving across from New Zealand about eight years ago when an apprentice. Last spring, he won the Gr.1 Caulfield Cup (2400m) aboard Durston and is currently equal fifth on the Melbourne jockeys' premiership with 22 wins.
Kelso said no plans have been made for further racing in Australian this autumn for Legarto, but he is aware a win or even a placing might be enough to earn a wildcard into the $5 million All-Star Mile two weeks later at The Valley.
“We want to come back in the spring with her so we might just have the one run, but we'll see where it (Guineas) takes us,” he said.
Meanwhile, triple Group One winning stablemate Levante is likely to push on to the Group 1 WFA Classic (1600m) at Otaki after a game run for third in Saturday's Group 1 BCD Group Sprint (1400m) at Te Rapa.
“She is going to Otaki, weather permitting,” Kelso said.
“She found the ground a bit hard on Saturday and I think she is looking for a mile. We will go to Otaki and then make a call after that.
“It was a terrific run on Saturday. She got back and got interfered with by the riderless horse (Mustang Valley). She found the line well again and she tries her heart out.”