Most observers were gloomily predicting another one-sided season after Mercedes recorded a comfortable one-two finish in the season opener in Australia, but two weeks later the picture was very different as Ferrari capitalized on searing track temperatures and some rare Mercedes mistakes to take a drought-breaking victory.
Coming off eight-straight wins and with Lewis Hamilton on pole, there was every reason to expect another Mercedes stroll. However, a track temperature of 61 degrees Celsius (142 F) at the start of the race exposed a chink in Mercedes' armour, as their tires degraded more quickly than Vettel's.
The turning point of the race came on just lap four when the safety car emerged. Vettel, who had been trailing Hamilton up to that point, elected to stay out while both Mercedes cars pitted. Vettel, who thrives in clear air at the front like few other drivers, was in control from then on, with Mercedes' worn rubber not up to the job of playing catch-up.
The race seemed alive until Hamilton's last stop on lap 38 of 56, when he had expected to switch to the softer tire and chase down Vettel who was on hards. However, he was also put onto the hards — "this is the wrong tire, man" was Hamilton's verdict over the radio — because there were no fresh medium-compound tires left, as the team had unwisely and unnecessarily used an extra set in Friday practice.
It was Ferrari's first victory since the 2013 Spanish Grand Prix. The 30-race gap between wins was the longest Ferrari drought for 21 years.
Vettel — in only his second race for the team after leaving Red Bull — recorded his first win since the 2013 Brazilian Grand Prix and the four-time world champion was overwhelmed in a way probably not seen since his first title in 2010.
After shouting on the team radio in delight — and in fluent Italian — he celebrated with crew members and danced around his car waving the Prancing Horse flag. He was in tears before taking to the top step of the podium, and choked up as he spoke.
"I am very, very happy and proud of today, we beat them fair and square, it was a great achievement," Vettel said. "Today is a very, very special day and will always remain a part of me."
His teammate Kimi Raikkonen finished fourth despite an unlucky qualifying that saw him start 11th and an early puncture that sent him to the back of the field. Williams driver Valtteri Bottas overtook teammate Felipe Massa in the closing laps to take fifth.
Toro Rosso's 17-year-old Max Verstappen claimed seventh to become the youngest points scorer in Formula One history.
He finished ahead of teammate Carlos Sainz Jr., with both Toro Rosso drivers outperforming their senior Red Bull team, with Daniil Kvyat ninth and Daniel Ricciardo 10th.
It was another humbling day for the once mighty McLaren team, with both Fernando Alonso and Jenson Button retiring with yet more technical gremlins in the new Honda engine.
Hamilton has the consolation of still leading the drivers' championship with 43 points to Vettel's 40 and should get much cooler and more favourable conditions at the next round in Shanghai on April 12. The Briton did acknowledge that Ferrari won on merit.
"I don't really know whether if I'd stayed out with him (after the safety car) it would have made much difference because they were probably just as good, if not a little better perhaps, on tire degradation," Hamilton said.
"It would have still been very, very close. But after that first stop, I had so much ground to catch up it was pretty much impossible."
Vettel has outpaced even his idol Michael Schumacher by winning in only his second Ferrari race, and spoke emotionally about his ailing German compatriot.
"When the gate opened at Maranello it was like a dream come true," Vettel said. "The last time I was there I watched Michael Schumacher over the fence and now I'm driving that red car.
"When I grew up, Michael was my hero and for all of us — and I speak for all the kids at the go-kart track at the time in Germany — we were looking up to him and when he turned up every year to look after us a little bit, it made our lives. So that's why today....I probably don't understand yet how special it is."