The extravaganza reflected the most geographically widespread Olympics in history.

It culminated in the lighting of two cauldrons, one at Milan's Arch of Peace and one in Cortina d'Ampezzo, the chic resort 400 kilometres (250 miles) from Milan that is hosting the women's alpine skiing.

Alberto Tomba and Deborah Compagnoni, two Italian skiing Olympic champions of the past, lit an intricate cauldron inspired by Leonardo da Vinci's knot patterns at Milan's Arch of Peace.

In the freezing mountain air of Cortina, the task fell to Sofia Goggia -- an Italian former gold medallist who had earlier taken part in a training run for the women's downhill event.

The ceremony in Milan showcased Italy's rich cultural heritage, with a nod to late fashion giant Giorgio Armani.

Performers at the San Siro show wore outsized heads of the three great masters of Italian opera -- Giuseppe Verdi, Giacomo Puccini and Gioachino Rossini while American diva Mariah Carey, in a white sequined dress with feathers, sang "Volare" in Italian and "Nothing is Impossible".

Italian tenor Andrea Bocelli got a rapturous reception after performing "Nessun Dorma" and dozens of models honoured Armani by streaming across the stage wearing red, green, and white trouser suits.

Italian President Sergio Mattarella declared the Games open after International Olympic Committee chief Kirsty Coventry told the competitors: "You remind us that we can be brave, that we can be kind, that we can get back up, no matter how hard we fall."

In a first, 2,900 athletes paraded in the venues closest to where they will compete in the February 6-22 Games, in a bid to minimise travel.

- Remarkable Vonn -

Earlier Friday, Lindsey Vonn, the biggest star at the Milan-Cortina Olympics, passed a crucial test of her injured knee.

The American skier successfully completed her first training run for the women's downhill event, despite competing with a ruptured anterior cruciate ligament.

It kept alive the 41-year-old's hopes of medal glory in Italy.

Vonn won her only Olympic gold at the Vancouver Games, 16 years ago, but also has two bronze medals.

A top-three placing in Sunday's final would cap a remarkable comeback from retirement that has been elevated to extraordinary by the injury she suffered in a pre-Olympics race.

Wearing a knee brace, Vonn completed the run at Cortina without apparent difficulty.

Before skiing she posted on Instagram: "Nothing makes me happier! No one would have believed I would be here... but I made it!!... I'm not going to waste this chance."

Asked by reporters after the race if everything was "all good", Vonn responded simply "yeah".

Competitive action in the figure skating began, with defending champions the United States taking an early lead in the team event thanks to world champion ice dancers Madison Chock and Evan Bates.

The men's downhill race, one of the prestige events, kicks off the first full day of action on Saturday.

China's freestyle skier Eileen Gu, one of the faces of the 2022 Games in Beijing, launches her bid for triple gold as the women's slopestyle gets underway at Livigno Snow Park.