Matts Olsson was seventh-fastest in the first run in 54.53sec but went all out in the second to record the fastest time of 52.45sec to win in a combined time of 1min 46.98sec.
He headed off Hans Olsson (no relation), who had been third-fastest in the first run and finished second overall in 1min 47.16sec, just pipping American Jimmy Cochran (1min 47.19sec).
Twenty-year-old Matts Olsson is a member of the Swedish World Cup team and is ranked 63 in the world in giant slalom.
He said he was excited about winning the Winter Games title.
"I am very happy to be the first winner.
"I didn't ski so well in the first run but I was better in the second.
"It was good to do a race like this.
"It's good for my World Cup preparation," he said.
He said it was a tough race.
"It was a difficult course in difficult conditions.
"It feels really good.
"I didn't think I'd do it, but it was really fun."
Olsson hoped yesterday's win would help in his selection for the Winter Olympics.
He said Coronet Peak was perfect training for his upcoming races.
Top seed Andre Myhrer, of Sweden, clocked the fastest first run in 53.68sec yesterday but failed to finish the second.
The leading New Zealander was 16-year-old Nick Prebble, of Christchurch, a member of the national development team.
He finished in 26th place in 1min 53.47sec, improving his world ranking.
Top-ranked New Zealander Ben Griffin, of Ohakune, did not finish the first run, while Olympic hopeful Tim Cafe, of Queenstown, completed his first run in 55.88sec but went out in the second.
"I was almost at the bottom but went off balance in one of the turns and before I knew it I was out.
"It's a bit of a shame," Cafe said.
He would make giant slalom his focus for the next few weeks, he said.
Eighty-five competitors from the United States, Sweden, Canada, France, Great Britain, Poland, Germany, the Ukraine, the Netherlands, Finland, the Czech Republic, Slovakia, Korea, Japan, Switzerland, Bulgaria, Monaco, Australia and New Zealand competed at Coronet Peak.
The Australia New Zealand Cup race has attracted international athletes in their build-up for the next World Cup series in the northern hemisphere and the 2010 Olympics in Vancouver.
The 36-gate course started on The Hurdle and finished in Eighth Basin.
Technical delegate Amanda Shaw, of Canada, said the conditions were challenging at Coronet Peak.
"In spite of snow and wind most of the day we were able to hold an excellent giant slalom," Shaw said.
"The Hurdle is an ideal giant slalom hill with its variety of rhythms and changes on the steeps and flats.
"We certainly had a high calibre field competing."
The only race to be cancelled yesterday was the adaptive racing.
The women's giant slalom and adaptive giant slalom will be held at Coronet Peak today.
