Leadbetter, as you would expect, has been mightily impressed with his 17-year-old student and thinks a major is just around the corner.
"Within the next year would not surprise me at all," Leadbetter said from his US base.
"She's 17 and hasn't played many majors, so it really is just a matter of time."
There are five majors on the women's professional tour and Leadbetter said the way Ko thrived under pressure yesterday proved that she had what it took to win the big ones, and believes her patient approach and short-game mastery is particularly suited to US Open set-ups.
Aussies lament missed opportunity to claim Lydia Ko
That's for the future, though, for the minute Leadbetter is happy to bask in Ko's stunning rookie season on tour.
"From day one she's had the temperament. It's the 15th club in her bag," the man who has coached the likes of Nick Faldo and Ernie Els said. "She's made an unbelievable impression on the golf world."
Leadbetter said ko had a great base when he started coaching her - she was coached by Guy Wilson during her formative years - and he had added some swing changes that sees her hitting more draws, meaning she has gained length.
"She's adapted to those swing changes really well. She's embraced them and is a really quick learner."
They spent their first six months together instigating the changes, now it is a matter of refining them to suit her game and entrenching them. Leadbetter knows he's struck it lucky in getting a client that is young enough not to have ingrained bad habits, and committed enough to become the very best. As well as a maturing swing, she has a maturing physique that is being complemented by a workout programme, which has enabled her to make the courses a bit "shorter".
"She's not the longest out there, but she's long enough," Leadbetter said.
The coach, ranked by the influential Golf Digest as second to Butch Harmon on a list of the "50 Greatest Teachers" in the US, said Ko's ability to adapt to the lifestyle required on the professional tour - "it's a world away from amateur golf" - has been another key to her success. Still, a lot of thought has gone into the risks of burn-out, particularly with an athlete who is so young and has already achieved so much. He pointed to the example of Michelle Wie, who "at the ripe-old age of 24" figured out a work-life balance that has seen her resurrect a career that stalled in her teens after an over-hyped start to her career.
"This is a long-term thing," Leadbetter said. "We don't want her burnt out, whether physically or mentally, after a couple of years. A lot of thought is going into this.
"It's a marathon, not a sprint."
FAMOUS LEADBETTER STUDENTS (Major wins in brackets)
Nick Faldo (6)
Ernie Els (4)
Nick Price (3)
Greg Norman (2)
Michelle Wie (1)
