The other four who have a strong chance to join O'Leary are sister Anna O'Leary (Kavanagh), Riley Bruce (Mt Aspiring College), Emma Winders (Columba College) and Julia Fauth (St Kevin's College).
Jack O'Leary (17), the elite rower in coach John Parnell's Otago Rowing Club squad, won the under-17 single sculls at Lake Karapiro last year and was runner-up in the under-18 event.
He made an international name for himself as a member of the New Zealand quadruple sculls that won the silver medal at the world junior championships in Lithuania last year.
His only event at this year's Maadi Cup is the under-18 single sculls.
''I feel great and I'm going to give it a good shot,'' he said.
''If I row my own race and perform to the best of my ability, I can win.''
''I just intend to keep relaxed and concentrate on making my boat go fast,'' he said.
Anna O'Leary (15), who was runner-up in the under-16 single sculls last year, will have a busier time.
She is entered in three single sculls events: under-16, under-17 and under-18.
Bruce (15) will be defending his title in the boys under-16 singles sculls and has also entered the under-17 event.
He showed he was in good form by winning three titles at the South Island secondary schools championships earlier this month.
He is teamed with Nathan Redai in the under-16 double sculls.
Winders, the daughter of former New Zealand premier lightweight single sculls champion Christine Winders, convincingly won the under-18 single sculls at the South Island championships.
She also won two silver and a bronze medal at the national club championships at Lake Karapiro last month.
Her only race at the Maadi Cup is the girls under-18 single sculls.
Fauth won a gold medal in the girls under-16 single sculls at last year's Maadi Cup at Lake Karapiro.
She also won a silver medal at the Maadi Cup last year with schoolmate Tiana Mihaere.
They are both competing in the girls under-17 single sculls, and Fauth will be partnered by Sydney Telfer in the under-17 double sculls.
The Maadi Cup is the largest rowing regatta held annually in New Zealand.
There will be 2108 pupils from 125 schools competing at Lake Ruataniwha this week.
There will be 1633 crews competing in 614 races across 50 events.
Other Otago rowers with a strong chance of reaching the podium are: Lucy Geddes and Ella Galletly (Dunstan High School) in the girls under 16 double sculls; Mark Taylor and James Scott (Waitaki Boys' High School), under-15 double sculls; Maysie Scott (Waitaki Girls' High School), under-18 single sculls; Courtney Shea and Claudia Paterson (St Hilda's Collegiate), under-18 double sculls; Eliza Adams and Zoe Sabonabaire (St Hilda's) under-17 double sculls; Tom Grave and Woody Kirkwood (John McGlashan College), under-16 double sculls.
