In a dream build-up for the world championships, dual Olympic medallist Andrew Lauterstein has broken both the Australian and Commonwealth 100m butterfly record.

Racing at the Giorgio Armani swim meet in Milan, the 22-year-old broke the 51-second barrier for the first time and set a new record and personal best of 50.92.

Head coach Alan Thompson says Lauterstein has been in ideal form during the past month and looks set to take that into this month's world championships in Rome.

"Andrew was very consistent during the Mare Nostrum series last month and then backed that up at the Paris Open where he won both the 50m and 100m butterfly in world class times," Thompson said.

"It's no surprise to see that he has continued on with that form in Italy and his next challenge will be to take that form in to a successful meet at the World Championships later this month."

The Gold Coast butterflyer took bronze at the Beijing Olympics when he touched in just behind Michael Phelps.

He later went on to take silver as part of Australia's 4x100m medley relay team after being narrowly beaten by the US team.

Lauterstein will now remain in Europe until he competes in both the men's 50m and 100m butterfly at the world championships.

SYDNEY AAP