Hall is one of five elite Otago athletes competing at the Australian championships.
The others are Tori Peeters (Taieri), Daniel O'Shea (Hill City-University) and Taieri AWD javelin throwers Rory McSweeney and Holly Robinson.
Hall (25) regained his senior men's discus title in Wellington and is targeting 60m.
He has improved dramatically since moving to Auckland for work two years ago.
He has added 4.25m to his distance in two years.
Hall threw a personal-best 58.25m at the New Zealand championships in Wellington to better his own Otago record by 1.19m.
He now trains with Matt Dellow's throwing squad.
''He has added weight and bulked up a lot,'' former coach Raylene Bates said.
''His strength and power is the best it's ever been.''
His first highlight came in February when he broke the Otago senior men's discus record of 56.86m that Robin Tait (Ariki) held for 48 years.
Hall threw 57.06m.
''I was thrilled and happy to see Marshall's performance,'' Bates said.
Peeters, who is coached by Bates, had broken the national women's aged 20 record earlier in the season and it was her dream to break the senior record.
She did this with a winning throw of 54.45m in Wellington on Sunday to beat the 1999 record of Kirsten Hellier, who won a silver medal at the Commonwealth Games in 1994.
The Commonwealth Games qualifying standard of 57m is getting closer and Peeters will have a crack at it when she competes in Melbourne.
''We are not focused on that,'' Bates said.
''The next target is to get over 55m.''
The Australian championships will be Peeters' first big meeting.
The field includes the world championship silver medallist, the Commonwealth Games gold medallist and the top five throwers in the world.
O'Shea is coached by Brent Ward and needs a big result to force himself into Commonwealth Games contention.
The Games qualifying standard for the 400m hurdles is 49.70sec and none of the three contenders has cracked it.
Waikato-Bay of Plenty hurdler Michael Cochrane tops the list with 49.72sec and is followed by team-mate Cameron French (50.16sec), who won the New Zealand title in Wellington.
O'Shea's best time this season is 50.57sec.
It was at the Australian championships last season that O'Shea broke through to beat Olympian Roger Johnson's 41-year-old Otago record.
McSweeney threw a season best when he won the AWD javelin with 42.73m. His best is the 49.15m he threw at the Paralympic world championships at Lyon last year before he had major reconstruction surgery on his knee.
''To compete at the nationals was an amazing feat for him,'' Bates said.
''We didn't expect him to be ready.''
Robinson won the AWD javelin gold medal with 34.06m, her second-best throw.
She will be trying to break the New Zealand record in Melbourne.
