A broken rear anti-rollbar left Alonso only 10th on the grid and seemingly in danger of seeing his Formula 1 championship lead slashed.
But instead he stretched his advantage to 37 points over new second place man and race-winner Lewis Hamilton by charging to third, while both Red Bulls retired.
"It was a perfect Sunday for us," said Alonso. "After the problem yesterday it was not easy to think about victory.
"So if you are not going to win, the podium is the next target.
"All the simulations and predictions said we would never finish on the podium, so it was much better than expected, and Jenson [Button] was out of the race and so were the two Red Bulls, so the perfect Sunday."
During his charge up the order, Alonso had a battle with Vettel that included the Ferrari being edged onto the Curva Grande grass. Vettel was given a drive-through penalty for the incident, which Alonso felt left his car with damage.
"I lost 10 laps behind him so I lost whatever seconds at that moment after the incident, and also the laps behind him," said Alonso.
"For sure the car is damaged because I was jumping in the gravel at 330km/h. I don't think the floor is completely fine after those jumps."
Vettel and Alonso had a similar incident in last year's race, but on that occasion it was the Ferrari defending and no penalty was issued.
"Last year was not a penalty and this year is a penalty," said Alonso. "That is the big difference for the people that understand this."
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