Caitlin Peirce won her home course for a second straight year as Japan's Riura Matsui came from the clouds to claim victory at the South Australian Amateur Classic and the Rene Erichsen Salver at Royal Adelaide Golf Club on Friday.

Peirce led the 72-hole tournament from start to finish after she jumped out of the blocks with a bogey free seven-under par first round 66 that included her lone eagle of the week.

The 20-year-old agricultural science student followed up her opening effort with consecutive 70s before a final round 74 was enough to win by four shots from Japan's Fuka Suga at 12-under par.

The victory continues Peirce's dominance in her home state as she won last year's edition of this event by six shots and took out the South Australian Amateur in September with a string of convincing match play performances.

Earlier this month, Peirce was the best of the Australians at the Women's Amateur Asia-Pacific in Singapore with a tied 13th finish.

Matsui saved his best golf for last with a seven-under final round 65 to edge out South Australian Jack Buchanan and New South Welshman Jeffrey Guan by a shot at eight-under.

The reigning Japanese Junior champion charged into the lead with four straight birdies at his final four holes - the first, second, third and fourth as players teed off the fifth and 14th throughout the tournament.

Matsui made four other birdies earlier in his round and his stunning late burst set a target for the other contenders to chase after he had produced rounds of 70, 68 and 76 across the three previous days.

Buchanan, who led after 18, 36 and 54 holes, teed off an hour and 20 minutes later than his Japanese rival and his lead began to dwindle away following two bogeys to start the day and a back nine that included a double bogey and another two bogeys.

With two holes to play, Buchanan was one shot shy of Matsui's clubhouse mark but he levelled things up with a birdie at the par-4 third.

Heartbreak came for the Glenelg member at the last however with a bogey to sign for a final round 75.

Guan on the other hand birdied three of his last six holes to jump into his eventual share of second with a second straight round of 71.

Final scores