The Swede snatched the slalom globe by winning the last two races of the season last winter to narrowly beat Austria's Marcel Hirscher, the overall World Cup champion.
Myhrer again beat Hirscher by a 0.06 of a second margin to triumph in a combined time of one minute 49.55 seconds.
World silver medallist Jens Byggmark completed a fine day for the Swedes by taking third place, 0.61 behind his team mate in difficult conditions with rain and fog forcing the skiers to take risks.
Myhrer's fifth World Cup victory was an important one as the 29-year-old Swede, also known for his guitar skills,needed to prove his victory in the 2012 World Cup owed nothing to chance.
"I spent the holidays doing nothing. I just rested as my back was hurting. But now I feel well and I trained well," he said.
"To see Jens and Marcel go down and take so many risks was an inspiration to try as hard."
A winner in Schladming last season, Myhrer said the world title in the Austrian slalom haven in February was his main goal of the season.
Hirscher was also delighted by his runner-up spot as he had never made it to the podium in Levi.
"It's not a course for me. I think I have never made it into the top 10 here," he said.
The difference was that the Austrian was using for the first time a new line of skis he personally designed and also took a relaxed approach to the competition.
"I tried not to think about the race. I just drank beer. As for my new skis I felt as excited as a kid building a model," he said.
"I know that everybody back home expects me to win every race but for me, it's a perfect start to the season. It's not about defending my World Cup title, it's about skiing well," he added.
Third in the opening giant slalom two weeks ago in Soelden, Hirscher was named Austrian sportsman of the year a week ago and he leads the World Cup overall standings on 140 points, ahead of Italy's Manfred Moelgg and Soelden winner Ted Ligety of the US.
Byggmark's third spot was all the more praiseworthy as he nearly crashed twice and had not made it on a World Cup rostrum since 2008. But his most significant victories in Kitzbuehel in 2007 were earned in the same swashbuckling fashion.