Japanese import Tosen Stardom’s outstanding win in Saturday's $500,000 Toorak Handicap at Caulfield has strengthened the case for backing the Deep Impact sire-line in Australia.

Arrowfield Stud stands the only two G1-winning sons of Deep Impact available to breeders outside Japan – real Impact and Mikki Isle.

Real Impact’s first Australian foals arrive this spring while Mikki Isle, Japan's Champion Sprinter-Miler in 2016, is serving his first book of Australian mares.

Tosen Stardom became Deep Impact's 31st G1 winner when he carried the topweight of 57.5 kg to win the Toorak Handicap for a syndicate led by Australian Bloodstock.

Bred and still part-owned by Katsumi Yoshida's Northern Racing, Tosen Stardom (Deep Impact x Admire Kirameki by End Sweep) is his sire’s second G1 winner from only three Australian runners.

The pioneer was Real Impact. He raced in Sydney in the autumn of 2015, winning the G1 George Ryder Stakes and finishing a close second in the G1 Doncaster Mile.

At the same Sydney carnival Tosen Stardom was second in the G1 Ranvet Stakes and fifth in Criterion's G1 Queen Elizabeth Stakes.

Tosen Stardom, also placed twice in Melbourne G1 sprints this year, has won six races and $2.1 million.

His spring options now include the G1 WS Cox Plate at Moonee Valley, the G1 Emirates Stakes or the G1 Cantala Stakes, now known as the Kennedy Mile, on the last day of Cup Week at Flemington.

Deep Impact's towering dominance in Japan is well-established but his international record, from around 30 runners outside Japan, is equally imposing.

Seven of his international performers are G1 winners – Gentildonna (Dubai), A Shin Hikari (France/Hong Kong), Beauty Parlour (France), Real Steel and Vivlos (Dubai), as well as Real Impact and Tosen Stardom.

Deep Impact is well on the way to securing his sixth Japanese Sires' premiership in 2017 with 18 stakeswinners and almost $A53 million prizemoney.

He is about $A13 million ahead of King Kamehameha and is also heading the 2YO and 3YO sires' tables.

Real Impact's first Japanese foals were sold at this year's JRHA Select Sale where Australian agent Robert Roulston paid approximately $A330,000 for his filly from German G2 winner Selkis (Monsun).

“I sent three mares to Real Impact in his first year, and when I saw his foals here I really loved them. They’re nice types - I’m quite bullish about Real Impact after seeing his foals,” Roulston said.